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

backend/internal/server/router.go

@@ -1,6 +1,8 @@
 package server
 
 import (
+	"log"
+
 	"github.com/Wei-Shaw/sub2api/internal/config"
 	"github.com/Wei-Shaw/sub2api/internal/handler"
 	middleware2 "github.com/Wei-Shaw/sub2api/internal/server/middleware"
@@ -20,6 +22,7 @@ func SetupRouter(
 	apiKeyAuth middleware2.APIKeyAuthMiddleware,
 	apiKeyService *service.APIKeyService,
 	subscriptionService *service.SubscriptionService,
+	settingService *service.SettingService,
 	cfg *config.Config,
 ) *gin.Engine {
 	// 应用中间件
@@ -27,9 +30,17 @@ func SetupRouter(
 	r.Use(middleware2.CORS(cfg.CORS))
 	r.Use(middleware2.SecurityHeaders(cfg.Security.CSP))
 
-	// Serve embedded frontend if available
+	// Serve embedded frontend with settings injection if available
 	if web.HasEmbeddedFrontend() {
-		r.Use(web.ServeEmbeddedFrontend())
+		frontendServer, err := web.NewFrontendServer(settingService)
+		if err != nil {
+			log.Printf("Warning: Failed to create frontend server with settings injection: %v, using legacy mode", err)
+			r.Use(web.ServeEmbeddedFrontend())
+		} else {
+			// Register cache invalidation callback
+			settingService.SetOnUpdateCallback(frontendServer.InvalidateCache)
+			r.Use(frontendServer.Middleware())
+		}
 	}
 
 	// 注册路由