chore(client): 优化日志输出并清理测试代码

1. 引入全局 `CONFIG.DEBUG` 配置项（默认为 `false`），将所有 `Utils.log(DEBUG, ...)` 的大量扫描和推算日志默认隐藏，避免刷屏 CC 终端，需要时可通过配置文件开启。
2. 移除了排查 NBT 结构时添加的 `stop_dump.json` 导出逻辑，保持主机系统文件整洁。

station_broadcast.lua

@@ -18,7 +18,7 @@ local CONFIG = {
     ALERT_COOLDOWN_MS = 300000,
     APPROACHING_COOLDOWN_MS = 120000,
     APPROACHING_STABLE_MS = 5000,
-    DEBUG = true
+    DEBUG = false
 }
 
 local dfpwm = require "cc.audio.dfpwm"
@@ -154,6 +154,7 @@ end
 local Utils = {}
 
 function Utils.log(level, message)
+    if level == "DEBUG" and not CONFIG.DEBUG then return end
     local timestamp = os.date("%H:%M:%S")
     local entryText = string.format("[%s][%s] %s", timestamp, level, message)
     local entry = { level = level, text = entryText }
@@ -2640,16 +2641,6 @@ function Main.loop()
                 cleanupTimestampMap(State.announcedAlerts, now, tonumber(CONFIG.ALERT_COOLDOWN_MS) or 300000)
                 
                 for i, stop in ipairs(data.TrainStops) do
-                    -- [DEBUG] Dump first stop to file for inspection
-                    if i == 1 and not State.dumpedStop then
-                        State.dumpedStop = true
-                        local f = fs.open("stop_dump.json", "w")
-                        if f then
-                            f.write(textutils.serializeJSON(stop))
-                            f.close()
-                            Utils.log("DEBUG", "Dumped stop structure to stop_dump.json")
-                        end
-                    end
                     local st = stop.Station
                     if st then
                         local trainName = st.TrainName or "Unknown"