修复：埋点接线与三处偏差（sessionId/eventId/设备信息）

- 生产接线修复：app.dart 组装时传 analytics 实例给 ApiAuthRepository（_buildRepository），修复 M1 遗留的「生产环境 _analytics 恒为 null、挂接点空转」问题
- sessionId 生命周期：新建 SessionTracker (WidgetsBindingObserver)，冷启动生成 UUIDv7、后台超 30 分钟换新、未超阈值沿用原值，不再每事件随机生成
- eventId 改 UUIDv7：对齐 13 号规范（uuid 包已在依赖，直接用 v7()），保留插入时间局部性
- appVersion 动态注入：package_info_plus（新增依赖）异步读取后 setAppVersion，不再硬编码 '1.0.0+1'
- osVersion 动态读取：Platform.operatingSystemVersion 正则提取主版本（如 android-14），不再硬编码
- 队列顺手加固：上传失败批次重回队首而非整批丢弃（一行级缓解，分段持久化属 M2 第二波）

测试新增 9 例：session_tracker_test（5 例：冷启动/短后台/长后台/级联状态/连续幂等），analytics_service_test 补强 4 例（UUIDv7/sessionId 不再逐事件生成/appVersion 可注入/失败重回队列）。

验收对照（06 号报告 §5.1 六条）：1✓ SessionTracker 新建、2✓ 三条语义、3✓ 同会话 sessionId 一致、4✓ sessionId 为 UUID 不持久化、5✓ 单测 3 例（实际 5 例）、6✓ 真机脚本（开发者手测）。

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

lib/app/app.dart

@@ -1,4 +1,10 @@
 import 'package:flutter/material.dart';
+import 'package:package_info_plus/package_info_plus.dart';
+import 'package:patbond_flutter/analytics/analytics_page_name.dart';
+import 'package:patbond_flutter/analytics/analytics_route_observer.dart';
+import 'package:patbond_flutter/analytics/analytics_service.dart';
+import 'package:patbond_flutter/analytics/page_view_tracker.dart';
+import 'package:patbond_flutter/analytics/session_tracker.dart';
 import 'package:patbond_flutter/core/network/api_client.dart';
 import 'package:patbond_flutter/core/network/token_refresher.dart';
 import 'package:patbond_flutter/core/theme/app_theme.dart';
@@ -24,6 +30,10 @@ class _AppState extends State<App> {
   late final AppState appState;
   late final SessionManager sessionManager;
   late final AuthRepository authRepository;
+  late final SessionTracker _sessionTracker;
+  late final AnalyticsService _analytics;
+  late final PageViewTracker _pageViewTracker;
+  late final AnalyticsRouteObserver _routeObserver;
 
   @override
   void initState() {
@@ -32,7 +42,37 @@ class _AppState extends State<App> {
     sessionManager =
         widget.sessionManager ??
         SessionManager(store: const SecureTokenStore());
+
+    _sessionTracker = SessionTracker();
+    WidgetsBinding.instance.addObserver(_sessionTracker);
+
+    _analytics = AnalyticsService(
+      apiBaseUrl: patbondApiBaseUrl,
+      getAccessToken: () => sessionManager.accessToken,
+      getSessionId: () => _sessionTracker.sessionId,
+    );
+    _initAppVersion();
+
+    _pageViewTracker = PageViewTracker(_analytics.trackEvent);
+    _routeObserver = AnalyticsRouteObserver(
+      tracker: _pageViewTracker,
+      resolveRootPage: _resolveRootPage,
+    );
+
     authRepository = widget.authRepository ?? _buildRepository();
+
+    // 认证状态切换补点（根路由 AnimatedSwitcher 无路由事件）
+    sessionManager.addListener(_reportAuthStateChange);
+  }
+
+  /// 异步读取 appVersion 并注入 analytics（启动后台任务，不阻塞渲染）。
+  Future<void> _initAppVersion() async {
+    try {
+      final info = await PackageInfo.fromPlatform();
+      _analytics.setAppVersion('${info.version}+${info.buildNumber}');
+    } catch (error) {
+      // 读取失败回退 'unknown'（AnalyticsService 构造默认值已兜底）。
+    }
   }
 
   AuthRepository _buildRepository() {
@@ -47,11 +87,33 @@ class _AppState extends State<App> {
       api: api,
       session: sessionManager,
       refresher: refresher,
+      analytics: _analytics,
     );
   }
 
+  AnalyticsPageName? _resolveRootPage() {
+    // 回栈到无名根路由时解析当前认证状态页/主壳 Tab
+    return switch (sessionManager.status) {
+      AuthStatus.unknown => null,
+      AuthStatus.unauthenticated => AnalyticsPageName.login,
+      AuthStatus.authenticated => _pageViewTracker.currentTab,
+    };
+  }
+
+  void _reportAuthStateChange() {
+    // 认证状态机切页补点（03 §3.2 非路由曝光 1/2）
+    final page = switch (sessionManager.status) {
+      AuthStatus.unauthenticated => AnalyticsPageName.login,
+      AuthStatus.authenticated => _pageViewTracker.currentTab,
+      AuthStatus.unknown => null,
+    };
+    if (page != null) _pageViewTracker.report(page);
+  }
+
   @override
   void dispose() {
+    sessionManager.removeListener(_reportAuthStateChange);
+    WidgetsBinding.instance.removeObserver(_sessionTracker);
     appState.dispose();
     if (widget.sessionManager == null) sessionManager.dispose();
     super.dispose();
@@ -74,6 +136,7 @@ class _AppState extends State<App> {
         return MainShellPage(
           key: const ValueKey('shell'),
           appState: appState,
+          pageViewTracker: _pageViewTracker,
           onLogout: authRepository.logout,
         );
     }
@@ -85,6 +148,7 @@ class _AppState extends State<App> {
       title: 'Patbond',
       debugShowCheckedModeBanner: false,
       theme: buildAppTheme(),
+      navigatorObservers: [_routeObserver],
       home: ListenableBuilder(
         listenable: sessionManager,
         builder: (context, _) {