feat(全栈): 实现简易模式核心功能

**功能概述**：
实现简易模式(Simple Mode)，为个人用户和小团队提供简化的使用体验，隐藏复杂的分组、订阅、配额等概念。

**后端改动**：
1. 配置系统
   - 新增 run_mode 配置项（standard/simple）
   - 支持环境变量 RUN_MODE
   - 默认值为 standard

2. 数据库初始化
   - 自动创建3个默认分组：anthropic-default、openai-default、gemini-default
   - 默认分组配置：无并发限制、active状态、非独占
   - 幂等性保证：重复启动不会重复创建

3. 账号管理
   - 创建账号时自动绑定对应平台的默认分组
   - 如果未指定分组，自动查找并绑定默认分组

**前端改动**：
1. 状态管理
   - authStore 新增 isSimpleMode 计算属性
   - 从后端API获取并同步运行模式

2. UI隐藏
   - 侧边栏：隐藏分组管理、订阅管理、兑换码菜单
   - 账号管理页面：隐藏分组列
   - 创建/编辑账号对话框：隐藏分组选择器

3. 路由守卫
   - 限制访问分组、订阅、兑换码相关页面
   - 访问受限页面时自动重定向到仪表板

**配置示例**：
```yaml
run_mode: simple

run_mode: standard
```

**影响范围**：
- 后端：配置、数据库迁移、账号服务
- 前端：认证状态、路由、UI组件
- 部署：配置文件示例

**兼容性**：
- 简易模式和标准模式可无缝切换
- 不需要数据迁移
- 现有数据不受影响

backend/cmd/server/main.go

@@ -107,6 +107,14 @@ func runSetupServer() {
 }
 
 func runMainServer() {
+	cfg, err := config.Load()
+	if err != nil {
+		log.Fatalf("Failed to load config: %v", err)
+	}
+	if cfg.RunMode == config.RunModeSimple {
+		log.Println("⚠️  WARNING: Running in SIMPLE mode - billing and quota checks are DISABLED")
+	}
+
 	buildInfo := handler.BuildInfo{
 		Version:   Version,
 		BuildType: BuildType,

backend/cmd/server/wire_gen.go

@@ -49,7 +49,7 @@ func initializeApplication(buildInfo handler.BuildInfo) (*Application, error) {
 	emailQueueService := service.ProvideEmailQueueService(emailService)
 	authService := service.NewAuthService(userRepository, configConfig, settingService, emailService, turnstileService, emailQueueService)
 	userService := service.NewUserService(userRepository)
-	authHandler := handler.NewAuthHandler(authService, userService)
+	authHandler := handler.NewAuthHandler(configConfig, authService, userService)
 	userHandler := handler.NewUserHandler(userService)
 	apiKeyRepository := repository.NewApiKeyRepository(db)
 	groupRepository := repository.NewGroupRepository(db)
@@ -62,7 +62,7 @@ func initializeApplication(buildInfo handler.BuildInfo) (*Application, error) {
 	usageHandler := handler.NewUsageHandler(usageService, apiKeyService)
 	redeemCodeRepository := repository.NewRedeemCodeRepository(db)
 	billingCache := repository.NewBillingCache(client)
-	billingCacheService := service.NewBillingCacheService(billingCache, userRepository, userSubscriptionRepository)
+	billingCacheService := service.NewBillingCacheService(billingCache, userRepository, userSubscriptionRepository, configConfig)
 	subscriptionService := service.NewSubscriptionService(groupRepository, userSubscriptionRepository, billingCacheService)
 	redeemCache := repository.NewRedeemCache(client)
 	redeemService := service.NewRedeemService(redeemCodeRepository, userRepository, subscriptionService, redeemCache, billingCacheService)
@@ -128,7 +128,7 @@ func initializeApplication(buildInfo handler.BuildInfo) (*Application, error) {
 	handlers := handler.ProvideHandlers(authHandler, userHandler, apiKeyHandler, usageHandler, redeemHandler, subscriptionHandler, adminHandlers, gatewayHandler, openAIGatewayHandler, handlerSettingHandler)
 	jwtAuthMiddleware := middleware.NewJWTAuthMiddleware(authService, userService)
 	adminAuthMiddleware := middleware.NewAdminAuthMiddleware(authService, userService, settingService)
-	apiKeyAuthMiddleware := middleware.NewApiKeyAuthMiddleware(apiKeyService, subscriptionService)
+	apiKeyAuthMiddleware := middleware.NewApiKeyAuthMiddleware(apiKeyService, subscriptionService, configConfig)
 	engine := server.ProvideRouter(configConfig, handlers, jwtAuthMiddleware, adminAuthMiddleware, apiKeyAuthMiddleware, apiKeyService, subscriptionService)
 	httpServer := server.ProvideHTTPServer(configConfig, engine)
 	tokenRefreshService := service.ProvideTokenRefreshService(accountRepository, oAuthService, openAIOAuthService, geminiOAuthService, configConfig)