fix(rail-map): 修复多线路站点坐标计算并优化线路渲染

新增按规范站名分组计算平均Y坐标的逻辑，解决同一站点对应多代码时的位置偏移问题。将SVG线路的直线段替换为贝塞尔曲线提升视觉流畅度，同时简化站点标记和辅助线的绘制代码，移除冗余的排序操作。

web/ticket-order.js

@@ -190,10 +190,24 @@
           }
 
           stationYByCanonical = {};
+          const ysByCanonical = {};
           for (const c of Object.keys(primaryLineByStation)) {
               const li = primaryLineByStation[c];
               if (li == null) continue;
-              stationYByCanonical[c] = baseY + li * lineGapY;
+              const canonical = stationCanonicalByCode[c] || c;
+              if (!ysByCanonical[canonical]) ysByCanonical[canonical] = [];
+              ysByCanonical[canonical].push(baseY + li * lineGapY);
+          }
+          
+          const canonicalY = {};
+          for (const canonical of Object.keys(ysByCanonical)) {
+              const ys = ysByCanonical[canonical];
+              canonicalY[canonical] = ys.reduce((a,b) => a+b, 0) / ys.length;
+          }
+
+          for (const c of Object.keys(primaryLineByStation)) {
+              const canonical = stationCanonicalByCode[c] || c;
+              stationYByCanonical[c] = canonicalY[canonical];
           }
 
           const allStations = Object.keys(primaryLineByStation);
@@ -229,7 +243,10 @@
                   
                   let d = `M ${pts[0].x} ${pts[0].y}`;
                   for (let i = 1; i < pts.length; i++) {
-                      d += ` L ${pts[i].x} ${pts[i].y}`;
+                      const prev = pts[i-1];
+                      const curr = pts[i];
+                      const midX = (prev.x + curr.x) / 2;
+                      d += ` C ${midX} ${prev.y}, ${midX} ${curr.y}, ${curr.x} ${curr.y}`;
                   }
                   svgContent += `<path d="${d}" fill="none" stroke="${li.color}" stroke-width="8" stroke-linecap="round" stroke-linejoin="round" />`;
               }
@@ -238,11 +255,10 @@
           for (const canonical of Object.keys(stationCodesByCanonical)) {
               const codes = (stationCodesByCanonical[canonical] || []).filter(code => Number.isFinite(stationYByCanonical[code]));
               if (codes.length < 2) continue;
-              const ys = codes.map(code => stationYByCanonical[code]).sort((a, b) => a - b);
               const x = stationXByCanonical[canonical];
-              const labelY = ys[ys.length - 1] + 34;
-              svgContent += `<line x1="${x}" y1="${ys[0]}" x2="${x}" y2="${ys[ys.length - 1]}" stroke="#cbd5e1" stroke-width="12" stroke-linecap="round" opacity="0.98" />`;
-              svgContent += `<circle cx="${x}" cy="${(ys[0] + ys[ys.length - 1]) / 2}" r="7" fill="#ffffff" stroke="#111827" stroke-width="3" />`;
+              const y = stationYByCanonical[codes[0]];
+              const labelY = y + 34;
+              svgContent += `<circle cx="${x}" cy="${y}" r="7" fill="#ffffff" stroke="#111827" stroke-width="3" />`;
               svgContent += `<rect x="${x - 42}" y="${labelY - 16}" width="84" height="24" rx="12" fill="rgba(241,245,249,0.92)" stroke="#cbd5e1" stroke-width="1.5" />`;
               svgContent += `<text x="${x}" y="${labelY}" text-anchor="middle" fill="#334155" font-size="13" font-weight="800">${getStationDisplayName(canonical)}</text>`;
               labelShownForCanonical.add(canonical);