fix(mining-app): 自动更新检查未触发 — 修复双重节流 + 添加调试日志

问题原因:
1. checkForUpdate() 未传 force:true，被 UpdateService 内部的60分钟
   SharedPreferences 间隔二次节流，导致实际请求被跳过
2. 缺少日志输出，无法诊断检查流程是否执行

修复:
- checkForUpdate(force: true) 跳过内部60分钟限制，
  因为 MainShell 已有自己的90-300秒随机冷却节流
- 在 initState / dispose / didChangeAppLifecycleState /
  _checkForUpdateIfNeeded 各关键节点添加 debugPrint 日志，
  方便 flutter run 控制台追踪完整检查流程

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/mining-app/lib/presentation/widgets/main_shell.dart

@@ -22,20 +22,24 @@ class _MainShellState extends State<MainShell> with WidgetsBindingObserver {
   @override
   void initState() {
     super.initState();
+    debugPrint('[MainShell] initState called, adding WidgetsBindingObserver');
     WidgetsBinding.instance.addObserver(this);
     WidgetsBinding.instance.addPostFrameCallback((_) {
+      debugPrint('[MainShell] postFrameCallback → 触发首次更新检查');
       _checkForUpdateIfNeeded();
     });
   }
 
   @override
   void dispose() {
+    debugPrint('[MainShell] dispose called, removing WidgetsBindingObserver');
     WidgetsBinding.instance.removeObserver(this);
     super.dispose();
   }
 
   @override
   void didChangeAppLifecycleState(AppLifecycleState state) {
+    debugPrint('[MainShell] didChangeAppLifecycleState: $state');
     if (state == AppLifecycleState.resumed) {
       _checkForUpdateIfNeeded();
     }
@@ -45,29 +49,41 @@ class _MainShellState extends State<MainShell> with WidgetsBindingObserver {
     final now = DateTime.now();
 
     // 如果从未检查过，或者已过冷却时间，则检查
-    if (_nextCheckAllowedTime == null || now.isAfter(_nextCheckAllowedTime!)) {
+    if (_nextCheckAllowedTime != null && now.isBefore(_nextCheckAllowedTime!)) {
-      // 设置下次允许检查时间（90-300秒随机间隔）
+      debugPrint('[MainShell] 跳过更新检查，冷却中 (下次: $_nextCheckAllowedTime)');
-      final randomSeconds = 90 + Random().nextInt(211);
+      return;
-      _nextCheckAllowedTime = now.add(Duration(seconds: randomSeconds));
+    }
 
-      // 延迟3秒，避免启动时干扰用户
+    // 设置下次允许检查时间（90-300秒随机间隔）
-      await Future.delayed(const Duration(seconds: 3));
+    final randomSeconds = 90 + Random().nextInt(211);
+    _nextCheckAllowedTime = now.add(Duration(seconds: randomSeconds));
+    debugPrint('[MainShell] 准备检查更新，延迟3秒...');
+
+    // 延迟3秒，避免启动时干扰用户
+    await Future.delayed(const Duration(seconds: 3));
+    if (!mounted) {
+      debugPrint('[MainShell] widget 已 unmount，取消检查');
+      return;
+    }
+
+    try {
+      debugPrint('[MainShell] 开始调用 UpdateService.checkForUpdate(force: true)');
+      // force: true 跳过 UpdateService 内部的60分钟间隔限制
+      // 因为我们已有自己的90-300秒冷却节流
+      final result = await UpdateService.instance.checkForUpdate(force: true);
+      debugPrint('[MainShell] 检查结果: hasUpdate=${result.hasUpdate}, error=${result.error}');
       if (!mounted) return;
 
-      try {
+      if (result.hasUpdate && result.versionInfo != null) {
-        final result = await UpdateService.instance.checkForUpdate();
+        debugPrint('[MainShell] 发现新版本: ${result.versionInfo!.versionName}，弹出更新对话框');
-        if (!mounted) return;
+        await SelfHostedUpdater.show(
-
+          context,
-        if (result.hasUpdate && result.versionInfo != null) {
+          versionInfo: result.versionInfo!,
-          await SelfHostedUpdater.show(
+          isForceUpdate: result.versionInfo!.isForceUpdate,
-            context,
+        );
-            versionInfo: result.versionInfo!,
-            isForceUpdate: result.versionInfo!.isForceUpdate,
-          );
-        }
-      } catch (e) {
-        debugPrint('[MainShell] 检查更新失败: $e');
       }
+    } catch (e) {
+      debugPrint('[MainShell] 检查更新失败: $e');
     }
   }