fix(ui): 彻底修复深浅色主题切换及内部页面样式

- 恢复 variables.css 完整的 ClassicDark/ModernDark 等主题定义
- 恢复 nuxt.config.ts 的主题系统逻辑（默认改为 ClassicLight，保留切换能力）
- 修复 BackupManager / VotersModal / ProfileForm / LyricsModal / RequestForm / SongList / ScheduleList / StatsSlide / ArtistSlide 等数十处组件内部硬编码深色（#1a1a1a / #040e15 等）绕过主题的问题，全部改为使用 CSS 变量 (var(--bg-primary) 等)
- 这样实现了：在浅色模式下，所有页面均正确显示浅色；在深色模式下，又能正常呈现深色设计，且恢复了右上角的深浅色切换能力

app/assets/css/variables.css

@@ -1,13 +1,10 @@
-/* 全局CSS变量 - 统一配色方案（默认浅色ClassicLight，不依赖data-theme也能正常显示） */
+/* 全局CSS变量 - 统一配色方案 */
 :root {
-  /* 强制浅色基准值 - 即使 data-theme 缺失也保持浅色 */
-  color-scheme: light;
-
   /* 主色调 */
-  --primary: #1e40af;
-  --primary-hover: #1e3a8a;
-  --primary-light: rgba(30, 64, 175, 0.08);
-  --primary-border: rgba(30, 64, 175, 0.15);
+  --primary: #3b82f6;
+  --primary-hover: #2563eb;
+  --primary-light: rgba(59, 130, 246, 0.1);
+  --primary-border: rgba(59, 130, 246, 0.2);
 
   /* 成功色 */
   --success: #10b981;
@@ -33,25 +30,25 @@
   --info-light: rgba(59, 130, 246, 0.1);
   --info-border: rgba(59, 130, 246, 0.2);
 
-  /* 背景色 (默认 ClassicLight 浅色) */
-  --bg-primary: #ffffff;
-  --bg-secondary: #f5f7fa;
-  --bg-tertiary: #edf0f5;
-  --bg-quaternary: #d9dee7;
-  --bg-hover: #f0f3f8;
+  /* 背景色 */
+  --bg-primary: #111111;
+  --bg-secondary: #1a1a1a;
+  --bg-tertiary: #2a2a2a;
+  --bg-quaternary: #3a3a3a;
+  --bg-hover: #1f1f1f;
 
-  /* 文字颜色 (默认 ClassicLight 浅色) */
-  --text-primary: #1a2332;
-  --text-secondary: #4a5568;
-  --text-tertiary: #6b7280;
-  --text-quaternary: #9ca3af;
-  --text-disabled: #c5cbd3;
+  /* 文字颜色 */
+  --text-primary: #ffffff;
+  --text-secondary: #cccccc;
+  --text-tertiary: #888888;
+  --text-quaternary: #666666;
+  --text-disabled: #444444;
 
-  /* 边框颜色 (默认 ClassicLight 浅色) */
-  --border-primary: #e5e7eb;
-  --border-secondary: #d1d5db;
-  --border-tertiary: #9ca3af;
-  --border-quaternary: #6b7280;
+  /* 边框颜色 */
+  --border-primary: #1f1f1f;
+  --border-secondary: #2a2a2a;
+  --border-tertiary: #3a3a3a;
+  --border-quaternary: #4a4a4a;
 
   /* 阴影 */
   --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
@@ -135,16 +132,16 @@
   --card-hover-border: var(--border-tertiary);
   --card-shadow: var(--shadow-md);
 
-  /* 按钮颜色 - 浅色基准 */
+  /* 按钮颜色 */
   --btn-primary-bg: var(--primary);
   --btn-primary-hover: var(--primary-hover);
-  --btn-primary-text: #ffffff;
+  --btn-primary-text: var(--text-primary);
   --btn-primary-border: var(--primary-border);
 
-  --btn-secondary-bg: #f1f5f9;
-  --btn-secondary-hover: #e2e8f0;
-  --btn-secondary-text: #0f172a;
-  --btn-secondary-border: #cbd5e1;
+  --btn-secondary-bg: #3a3a3a;
+  --btn-secondary-hover: #4a4a4a;
+  --btn-secondary-text: var(--text-primary);
+  --btn-secondary-border: #555555;
 
   --btn-success-bg: var(--success);
   --btn-success-hover: var(--success-hover);
@@ -164,12 +161,12 @@
   --btn-disabled-bg: var(--bg-tertiary);
   --btn-disabled-text: var(--text-disabled);
 
-  /* 输入框颜色 - 浅色基准 */
-  --input-bg: #ffffff;
-  --input-border: #d1d5db;
+  /* 输入框颜色 */
+  --input-bg: var(--bg-tertiary);
+  --input-border: var(--border-tertiary);
   --input-border-focus: var(--primary);
   --input-text: var(--text-primary);
-  --input-placeholder: #9ca3af;
+  --input-placeholder: var(--text-quaternary);
   --input-shadow-focus: 0 0 0 3px var(--primary-light);
 
   /* 模态框颜色 */
@@ -200,27 +197,12 @@
   --spinner-primary: var(--primary);
   --spinner-secondary: var(--bg-tertiary);
 
-  /* 滚动条颜色 - 浅色基准 */
-  --scrollbar-track: #f1f5f9;
-  --scrollbar-thumb: #cbd5e1;
-  --scrollbar-thumb-hover: #94a3b8;
-
-  /* Surface 兼容别名 - 部分按钮/容器使用 surface-xxx */
-  --surface-primary: var(--bg-primary);
-  --surface-secondary: var(--bg-secondary);
-  --surface-tertiary: var(--bg-tertiary);
-  --surface-quaternary: var(--bg-quaternary);
+  /* 滚动条颜色 */
+  --scrollbar-track: var(--bg-tertiary);
+  --scrollbar-thumb: var(--bg-quaternary);
+  --scrollbar-thumb-hover: #4a4a4a;
 }
 
-/* 防深色兜底：覆盖 prefers-color-scheme: dark 对表单/根元素的自动影响 */
-@media (prefers-color-scheme: dark) {
-  :root {
-    color-scheme: light;
-  }
-}
-
-/* 浅色主题叠加层（与 data-theme 无关，确保始终为浅色；保留 data-theme 变量覆盖以兼容切换） */
-:root,
 :root[data-theme='light'],
 :root[data-theme='ClassicLight'],
 :root[data-theme='ModernLight'] {

app/components/Admin/BackupManager.vue

@@ -520,8 +520,8 @@ const formatFileSize = (bytes) => {
 /* 主容器 */
 .backup-manager {
   min-height: 100vh;
-  background: #1a1a1a;
-  color: #e5e5e5;
+  background: var(--bg-primary, #1a1a1a);
+  color: var(--text-primary, #e5e5e5);
   padding: 2rem;
   position: relative;
 }
@@ -535,13 +535,13 @@ const formatFileSize = (bytes) => {
 .header h3 {
   font-size: 2.5rem;
   font-weight: 700;
-  color: #ffffff;
+  color: var(--text-primary, #ffffff);
   margin: 0 0 1rem 0;
 }
 
 .header .description {
   font-size: 1.125rem;
-  color: #a0a0a0;
+  color: var(--text-secondary, #a0a0a0);
   margin: 0;
 }
 

app/components/Admin/VotersModal.vue

@@ -202,9 +202,9 @@ watch(
 }
 
 .modal-content {
-  background: #1a1a1a;
+  background: var(--surface-primary, var(--bg-primary, #1a1a1a));
   border-radius: 16px;
-  border: 1px solid #2a2a2a;
+  border: 1px solid var(--border-primary, #2a2a2a);
   width: 100%;
   max-width: 500px;
   max-height: 80vh;

app/components/Auth/ProfileForm.vue

@@ -224,24 +224,24 @@ const handleUpdateProfile = async () => {
 <style scoped>
 .custom-select-profile :deep(> .flex) {
   padding: 10px 16px;
-  background-color: #09090b;
-  border: 1px solid #27272a;
+  background-color: var(--input-bg, #09090b);
+  border: 1px solid var(--input-border, #27272a);
   border-radius: 0.75rem;
-  color: #f4f4f5;
+  color: var(--input-text, #f4f4f5);
   font-size: 0.875rem;
   line-height: 1.25rem;
   height: 46px;
 }
 
 .custom-select-profile :deep(> .flex:hover) {
-  border-color: #3f3f46;
+  border-color: var(--input-border-focus, #3f3f46);
 }
 
 .custom-select-profile :deep(> .border-blue-500\/50) {
-  border-color: rgba(34, 197, 94, 0.5) !important;
-  --tw-ring-color: rgba(34, 197, 94, 0.5);
+  border-color: var(--primary, rgba(34, 197, 94, 0.5)) !important;
+  --tw-ring-color: var(--primary-light, rgba(34, 197, 94, 0.5));
   box-shadow: var(--tw-ring-inset) 0 0 0 calc(1px + var(--tw-ring-offset-width)) var(--tw-ring-color);
-  background-color: #09090b !important;
+  background-color: var(--input-bg, #09090b) !important;
 }
 
 .custom-select-profile :deep(.text-\[11px\]) {

app/components/Songs/RequestForm.vue

@@ -3194,14 +3194,14 @@ defineExpose({
 }
 
 .search-input {
-  background: #040e15;
-  border: 1px solid #242f38;
+  background: var(--input-bg, #040e15);
+  border: 1px solid var(--input-border, #242f38);
   border-radius: 8px;
   padding: 0.6rem 0.85rem;
   font-family: 'MiSans', sans-serif;
   font-weight: 600;
   font-size: 15px;
-  color: rgba(255, 255, 255, 0.6);
+  color: var(--input-text, rgba(255, 255, 255, 0.6));
   flex: 1;
   min-width: 100px; /* 确保输入框不会缩到太小 */
 }
@@ -3484,14 +3484,14 @@ defineExpose({
 
 .form-input,
 .form-select {
-  background: #040e15;
-  border: 1px solid #242f38;
+  background: var(--input-bg, #040e15);
+  border: 1px solid var(--input-border, #242f38);
   border-radius: 8px;
   padding: 0.75rem 1rem;
   font-family: 'MiSans', sans-serif;
   font-weight: 600;
   font-size: 16px;
-  color: rgba(255, 255, 255, 0.6);
+  color: var(--input-text, rgba(255, 255, 255, 0.6));
   width: 100%;
 }
 

app/components/Songs/ScheduleList.vue

@@ -2188,9 +2188,9 @@ const vRipple = {
 .custom-select:focus,
 .custom-input:focus {
   outline: none;
-  border-color: var(--primary);
-  box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
-  background: #1a1a20;
+  border-color: var(--input-border-focus, var(--primary));
+  box-shadow: var(--input-shadow-focus, 0 0 0 3px rgba(102, 126, 234, 0.1));
+  background: var(--input-bg, #1a1a20);
 }
 
 .btn-icon {
@@ -3168,7 +3168,7 @@ const vRipple = {
 
   /* 日期选择弹窗 */
   .date-picker-content {
-    background: #1a1a1f;
+    background: var(--surface-primary, var(--bg-primary, #1a1a1f));
     border-radius: 20px 20px 0 0;
     width: 100%;
     max-width: 100%;

app/components/Songs/SongList.vue

@@ -1894,14 +1894,14 @@ const vRipple = {
 }
 
 .search-input {
-  background: #040e15;
-  border: 1px solid #242f38;
+  background: var(--input-bg, #040e15);
+  border: 1px solid var(--input-border, #242f38);
   border-radius: 8px;
   padding: 0.5rem 1rem;
   padding-right: 2.5rem;
   font-family: 'MiSans-Demibold', sans-serif;
   font-size: 14px;
-  color: rgba(255, 255, 255, 0.8);
+  color: var(--input-text, rgba(255, 255, 255, 0.8));
   width: 100%;
   transition: all 0.2s ease;
 }
@@ -2593,7 +2593,7 @@ button:disabled {
   }
 
   .semester-dropdown {
-    background: #1a1a1f;
+    background: var(--surface-primary, var(--bg-primary, #1a1a1f));
     border: none;
     border-radius: 12px;
     box-shadow: 0 10px 40px rgba(0, 0, 0, 0.4);

app/components/UI/LyricsModal.vue

@@ -953,8 +953,8 @@ onUnmounted(() => {
   position: relative;
   width: 100%;
   height: 100%;
-  background: #000000;
-  color: #ffffff;
+  background: var(--bg-primary, #000000);
+  color: var(--text-primary, #ffffff);
   overflow: hidden;
   display: flex;
   flex-direction: column;

app/components/year-review/ArtistSlide.vue

@@ -37,7 +37,7 @@ defineProps({
   align-items: center;
   justify-content: center;
   overflow: hidden;
-  background-color: #1a0b2e;
+  background-color: var(--surface-primary, var(--bg-primary, #1a0b2e));
 }
 
 .bg-overlay {

app/components/year-review/StatsSlide.vue

@@ -43,7 +43,7 @@ defineProps({
   align-items: center;
   justify-content: center;
   overflow: hidden;
-  background-color: #030712; /* gray-950 */
+  background-color: var(--surface-primary, var(--bg-primary, #030712));
 }
 
 .bg-gradient {

nuxt.config.ts

@@ -194,10 +194,6 @@ export default defineNuxtConfig({
           name: 'x-default-theme',
           content: process.env.NUXT_PUBLIC_DEFAULT_THEME || 'ClassicLight'
         },
-        {
-          name: 'x-enabled-themes',
-          content: process.env.NUXT_PUBLIC_ENABLED_THEMES || 'ClassicLight,ModernLight'
-        },
         { name: 'apple-mobile-web-app-capable', content: 'yes' },
         { name: 'apple-mobile-web-app-status-bar-style', content: 'black-translucent' },
         { name: 'apple-mobile-web-app-title', content: 'VoiceHub管理' },
@@ -210,28 +206,18 @@ export default defineNuxtConfig({
           tagPosition: 'head',
           children: [
             `(function(){try{`,
-            `  var k='voicehub:theme', d=document, r=d.documentElement, s=null, eff=null, def=null, list=[];`,
-            `  try{`,
-            `    var mt=d.querySelector('meta[name="x-enabled-themes"]');`,
-            `    if(mt && mt.content){list=String(mt.content).split(',').map(function(x){return x.replace(/^\\s+|\\s+$/g,'')}).filter(Boolean)}`,
-            `  }catch(e){list=[]}`,
-            `  try{`,
-            `    var md=d.querySelector('meta[name="x-default-theme"]');`,
-            `    if(md && md.content){def=md.content}`,
-            `  }catch(e){def=null}`,
-            `  if(!def){def='ClassicLight'}`,
-            `  if(list.length===0){list=['ClassicLight','ModernLight']}`,
-            `  function valid(t){`,
-            `    if(list.indexOf(t)!==-1){return t}`,
-            `    if(list.indexOf(def)!==-1){return def}`,
-            `    return list[0]`,
-            `  }`,
+            `  var k='voicehub:theme', d=document, r=d.documentElement, s=null, eff=null;`,
             `  try{s=localStorage.getItem(k)}catch(e){s=null}`,
-            `  if(!s){s=def}`,
-            `  else{s=valid(s)}`,
-            `  if(typeof s==='string' && (s==='System'||s==='system')){eff=window.matchMedia('(prefers-color-scheme: dark)').matches?'dark':'light'}`,
+            `  if(!s){`,
+            `    try{`,
+            `      var meta=document.querySelector('meta[name="x-default-theme"]');`,
+            `      if(meta && meta.content){s=meta.content}`,
+            `    }catch(e){s=null}`,
+            `    if(!s){s='ClassicLight'}`,
+            `  }`,
+            `  if(s==='System'||s==='system'){eff=window.matchMedia('(prefers-color-scheme: dark)').matches?'dark':'light'}`,
             `  else if(typeof s==='string'){eff=s.endsWith('Dark')||s==='dark'?'dark':(s.endsWith('Light')||s==='light'?'light':s)}`,
-            `  else{eff='light'}`,
+            `  else{eff='dark'}`,
             `  r.setAttribute('data-theme', (typeof s==='string'?s:eff));`,
             `  if(eff==='dark'){r.classList.add('dark'); r.classList.remove('light'); r.style.colorScheme='dark'}`,
             `  else if(eff==='light'){r.classList.add('light'); r.classList.remove('dark'); r.style.colorScheme='light'}`,