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>

frontend/src/api/connection-manager.ts

@@ -0,0 +1,199 @@
+/**
+ * 连接管理器 — 管理本地/远程传输层切换
+ */
+
+import type { FsTransport } from './transport'
+import { WailsTransport } from './wails-transport'
+import { HttpTransport } from './http-transport'
+
+export type ConnectionType = 'local' | 'remote'
+
+export interface ConnectionProfile {
+  id: string
+  name: string
+  host: string
+  port: number
+  token: string
+  type: ConnectionType
+  lastConnected?: number
+}
+
+export type ConnectionState = 'disconnected' | 'connecting' | 'connected' | 'error'
+
+const PROFILES_KEY = 'fs_connection_profiles'
+const ACTIVE_KEY = 'fs_active_connection'
+
+class ConnectionManagerImpl {
+  private _transport: FsTransport | null = null
+  private _profiles: ConnectionProfile[] = []
+  private _activeId: string | null = null
+  private _state: ConnectionState = 'disconnected'
+  private _stateChangeCallbacks: ((state: ConnectionState) => void)[] = []
+  private _connectSeq = 0
+
+  constructor() {
+    this.loadProfiles()
+    this.initDefaultLocal()
+  }
+
+  private initDefaultLocal() {
+    const localProfile: ConnectionProfile = {
+      id: 'local-default',
+      name: '本地',
+      host: '',
+      port: 0,
+      token: '',
+      type: 'local',
+    }
+    if (!this._profiles.find(p => p.id === localProfile.id)) {
+      this._profiles.unshift(localProfile)
+    }
+    // 默认连接本地
+    if (!this._activeId) {
+      this._activeId = localProfile.id
+    }
+    this.applyActive()
+  }
+
+  private loadProfiles() {
+    try {
+      const raw = localStorage.getItem(PROFILES_KEY)
+      if (raw) this._profiles = JSON.parse(raw)
+      this._activeId = localStorage.getItem(ACTIVE_KEY)
+    } catch { /* 首次使用 */ }
+  }
+
+  private saveProfiles() {
+    localStorage.setItem(PROFILES_KEY, JSON.stringify(this._profiles))
+    if (this._activeId) {
+      localStorage.setItem(ACTIVE_KEY, this._activeId)
+    }
+  }
+
+  private setState(state: ConnectionState) {
+    this._state = state
+    this.notifyChange()
+  }
+
+  private notifyChange() {
+    this._stateChangeCallbacks.forEach(cb => cb(this._state))
+  }
+
+  onStateChange(cb: (state: ConnectionState) => void) {
+    this._stateChangeCallbacks.push(cb)
+  }
+
+  get state(): ConnectionState {
+    return this._state
+  }
+
+  get profiles(): ConnectionProfile[] {
+    return [...this._profiles]
+  }
+
+  get activeProfile(): ConnectionProfile | null {
+    return this._profiles.find(p => p.id === this._activeId) ?? null
+  }
+
+  getTransport(): FsTransport {
+    if (!this._transport) {
+      this.applyActive()
+    }
+    return this._transport!
+  }
+
+  getFileServerBaseURL(): string {
+    if (this._transport instanceof HttpTransport) {
+      const profile = this.activeProfile
+      if (!profile) return ''
+      const scheme = profile.port === 443 ? 'https' : 'http'
+      const port = (profile.port === 80 || profile.port === 443) ? '' : `:${profile.port}`
+      return `${scheme}://${profile.host}${port}`
+    }
+    // Wails 模式返回空字符串，让 useFilePreview 走原有逻辑
+    return ''
+  }
+
+  isRemote(): boolean {
+    return this.activeProfile?.type === 'remote'
+  }
+
+  connect(profileId: string): void {
+    const profile = this._profiles.find(p => p.id === profileId)
+    if (!profile) return
+
+    this._activeId = profileId
+    this.saveProfiles()
+    this.applyActive()
+  }
+
+  disconnect(): void {
+    this._activeId = 'local-default'
+    this.saveProfiles()
+    this.applyActive()
+  }
+
+  addProfile(profile: Omit<ConnectionProfile, 'id'>): ConnectionProfile {
+    const newProfile: ConnectionProfile = {
+      ...profile,
+      id: crypto.randomUUID(),
+    }
+    this._profiles.push(newProfile)
+    this.saveProfiles()
+    this.notifyChange()
+    return newProfile
+  }
+
+  updateProfile(id: string, updates: Partial<ConnectionProfile>): void {
+    const idx = this._profiles.findIndex(p => p.id === id)
+    if (idx >= 0) {
+      this._profiles[idx] = { ...this._profiles[idx], ...updates }
+      this.saveProfiles()
+      // 仅当连接参数变化时重新应用（避免 lastConnected 等元数据更新触发死循环）
+      const REAPPLY_KEYS = ['host', 'port', 'token'] as const
+      const needsReapply = REAPPLY_KEYS.some(k => k in updates)
+      if (needsReapply && id === this._activeId) {
+        this.applyActive()
+      }
+      this.notifyChange()
+    }
+  }
+
+  removeProfile(id: string): void {
+    if (id === 'local-default') return // 不允许删除本地配置
+    this._profiles = this._profiles.filter(p => p.id !== id)
+    if (this._activeId === id) {
+      this._activeId = 'local-default'
+    }
+    this.saveProfiles()
+    this.applyActive()
+    this.notifyChange()
+  }
+
+  private applyActive() {
+    const profile = this.activeProfile
+    const seq = ++this._connectSeq
+    if (!profile || profile.type === 'local') {
+      this._transport = new WailsTransport()
+      this.setState('connected')
+    } else {
+      this.setState('connecting')
+      try {
+        this._transport = new HttpTransport(profile.host, profile.port, profile.token)
+        // 快速连通性检查（用轻量 ping 代替 getCommonPaths）
+        this._transport.getFileInfo('/').then(() => {
+          if (seq !== this._connectSeq) return // 已被后续连接覆盖
+          this.setState('connected')
+          this.updateProfile(profile.id!, { lastConnected: Date.now() })
+        }).catch(() => {
+          if (seq !== this._connectSeq) return
+          this.setState('error')
+        })
+      } catch {
+        this.setState('error')
+      }
+    }
+  }
+}
+
+export const connectionManager = new ConnectionManagerImpl()