fix: 添加前端静态文件服务，修复404问题

backend/internal/api/routes/routes.go

@@ -27,6 +27,12 @@ func SetupRoutes(r *gin.Engine) {
 	r.Use(middlewares.CORSMiddleware())
 
 	r.Static("/uploads", "./uploads")
+	r.Static("/assets", "./static/assets")
+	r.StaticFile("/favicon.ico", "./static/favicon.ico")
+
+	r.NoRoute(func(c *gin.Context) {
+		c.File("./static/index.html")
+	})
 
 	api := r.Group("/api")
 	{