重构：Wails v3 迁移 + 前端目录规范化 + Sidebar滚动优化

- web/ → frontend/ 目录重命名（Wails v3 标准结构）
- main.go: Middleware 修复 custom.js 404 + DevTools 延迟启动
- Sidebar: 收藏夹内部独立滚动 + 帮助区块固定底部
- useFavorites.ts: longPressTimer const→let 修复 TypeError
- App.vue: Arco Tabs padding-top 覆盖
- build: config.yml / Taskfile.yml 对齐官方模板，devtools build tag
- 新增 v3 bindings、vite.config.js、跨平台构建配置

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

internal/api/update_api.go

@@ -2,17 +2,15 @@ package api
 
 import (
 	"context"
-	"encoding/json"
 	"u-desk/internal/service"
 	"time"
-
-	"github.com/wailsapp/wails/v2/pkg/runtime"
 )
 
 // UpdateAPI 版本更新 API
 type UpdateAPI struct {
 	updateService *service.UpdateService
 	ctx           context.Context
+	eventEmitter  func(name string, data ...any)
 }
 
 // NewUpdateAPI 创建版本更新 API
@@ -22,11 +20,23 @@ func NewUpdateAPI(checkURL string) (*UpdateAPI, error) {
 	}, nil
 }
 
+// SetEventEmitter 设置事件发射器（由 App.ServiceStartup 注入）
+func (api *UpdateAPI) SetEventEmitter(emitter func(name string, data ...any)) {
+	api.eventEmitter = emitter
+}
+
 // SetContext 设置上下文（用于事件推送）
 func (api *UpdateAPI) SetContext(ctx context.Context) {
 	api.ctx = ctx
 }
 
+// emit 发送事件到前端
+func (api *UpdateAPI) emit(name string, data ...any) {
+	if api.eventEmitter != nil {
+		api.eventEmitter(name, data...)
+	}
+}
+
 // successResponse 构造成功响应
 func successResponse(data interface{}) map[string]interface{} {
 	return map[string]interface{}{"success": true, "data": data}
@@ -108,8 +118,7 @@ func (api *UpdateAPI) DownloadUpdate(downloadURL string) (map[string]interface{}
 				"downloaded": downloaded,
 				"total":      total,
 			}
-			progressJSON, _ := json.Marshal(progressInfo)
-			runtime.EventsEmit(api.ctx, "download-progress", string(progressJSON))
+			api.emit("download-progress", progressInfo)
 		}
 
 		time.Sleep(100 * time.Millisecond)
@@ -117,16 +126,14 @@ func (api *UpdateAPI) DownloadUpdate(downloadURL string) (map[string]interface{}
 
 		if err != nil {
 			errorInfo := map[string]interface{}{"error": err.Error()}
-			errorJSON, _ := json.Marshal(errorInfo)
-			runtime.EventsEmit(api.ctx, "download-complete", string(errorJSON))
+			api.emit("download-complete", errorInfo)
 		} else {
 			resultInfo := map[string]interface{}{
 				"success":   true,
 				"file_path": result.FilePath,
 				"file_size": result.FileSize,
 			}
-			resultJSON, _ := json.Marshal(resultInfo)
-			runtime.EventsEmit(api.ctx, "download-complete", string(resultJSON))
+			api.emit("download-complete", resultInfo)
 		}
 	}()