feat: 支持跟随系统深色/浅色模式（darkmode + theme.json + 主题检测）

src/utils/store.ts

@@ -262,8 +262,14 @@ export function setTheme(theme: ThemeMode) {
 /** 根据自动模式解析实际生效主题 */
 export function resolveTheme(mode: ThemeMode): 'light' | 'dark' {
   if (mode === 'auto') {
-    const info = Taro.getSystemInfoSync()
-    return info.theme === 'dark' ? 'dark' : 'light'
+    // 需 app.json 开启 darkmode 后 theme 字段才有效；getSystemInfoSync 已废弃，改用 getAppBaseInfo
+    try {
+      const info = Taro.getAppBaseInfo()
+      return info.theme === 'dark' ? 'dark' : 'light'
+    } catch {
+      const info = Taro.getSystemInfoSync()
+      return info.theme === 'dark' ? 'dark' : 'light'
+    }
   }
   return mode
 }