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>

build/ios/main_ios.go

@@ -0,0 +1,24 @@
+//go:build ios
+
+package main
+
+import (
+	"C"
+)
+
+// For iOS builds, we need to export a function that can be called from Objective-C
+// This wrapper allows us to keep the original main.go unmodified
+
+//export WailsIOSMain
+func WailsIOSMain() {
+	// DO NOT lock the goroutine to the current OS thread on iOS!
+	// This causes signal handling issues:
+	// "signal 16 received on thread with no signal stack"
+	// "fatal error: non-Go code disabled sigaltstack"
+	// iOS apps run in a sandboxed environment where the Go runtime's
+	// signal handling doesn't work the same way as desktop platforms.
+
+	// Call the actual main function from main.go
+	// This ensures all the user's code is executed
+	main()
+}