feat(settings): add home content customization and config injection

- Add home_content setting for custom homepage (HTML or iframe URL)
- Inject public settings into index.html to eliminate page flash
- Support ETag caching with automatic invalidation on settings update
- Add Vite plugin for dev mode settings injection
- Refactor HomeView to use appStore instead of local API calls

backend/internal/server/http.go

@@ -30,6 +30,7 @@ func ProvideRouter(
 	apiKeyAuth middleware2.APIKeyAuthMiddleware,
 	apiKeyService *service.APIKeyService,
 	subscriptionService *service.SubscriptionService,
+	settingService *service.SettingService,
 ) *gin.Engine {
 	if cfg.Server.Mode == "release" {
 		gin.SetMode(gin.ReleaseMode)
@@ -47,7 +48,7 @@ func ProvideRouter(
 		}
 	}
 
-	return SetupRouter(r, handlers, jwtAuth, adminAuth, apiKeyAuth, apiKeyService, subscriptionService, cfg)
+	return SetupRouter(r, handlers, jwtAuth, adminAuth, apiKeyAuth, apiKeyService, subscriptionService, settingService, cfg)
 }
 
 // ProvideHTTPServer 提供 HTTP 服务器