fix: 修复assets文件路径错误

- 修复通配符参数filepath只包含assets/后面的部分的问题
- 正确拼接assets/前缀以查找嵌入的静态资源文件

backend/cmd/main.go

@@ -262,15 +262,9 @@ func setupEmbeddedFrontend(r *gin.Engine) {
 	}
 
 	r.GET("/assets/*filepath", func(c *gin.Context) {
-		filepath := strings.TrimPrefix(c.Request.URL.Path, "/assets/")
+		filepath := c.Param("filepath")
-		file, err := distFS.Open(filepath)
-		if err != nil {
-			c.JSON(404, gin.H{"error": "asset not found"})
-			return
-		}
-		file.Close()
 		c.Header("Cache-Control", "public, max-age=31536000, immutable")
-		c.FileFromFS(c.Request.URL.Path, http.FS(distFS))
+		c.FileFromFS("assets/"+filepath, http.FS(distFS))
 	})
 
 	r.NoRoute(func(c *gin.Context) {