feat: Desktop Sync Client (Tauri) - Grundgeruest

Tauri 2 Desktop-Client mit:

Rust-Backend:
- MiniCloudApi: Login, Token-Refresh, Upload, Download, Sync-Tree,
  Sync-Changes, File-Locking (Lock/Unlock/Heartbeat)
- SyncEngine: Full-Sync (Server-Tree vs. lokales Dateisystem),
  Delta-Sync (nur Aenderungen seit letztem Sync), bidirektionaler
  Abgleich mit SHA-256 Checksummen, Ordner-Erstellung,
  Lock-Status-Pruefung vor Upload, Konflikt-Erkennung
- FileWatcher: Filesystem-Watcher (notify crate) fuer Echtzeit-
  Erkennung lokaler Aenderungen, filtert temp/hidden files

Vue-Frontend:
- Login-Screen: Server-URL, Benutzername, Passwort
- Main-Screen: Sync-Ordner setzen, Sync starten, Dateiliste mit
  Lock-Status, Sync-Protokoll
- Dark-Mode Support

Tauri-Kommandos: login, set_sync_dir, start_sync, delta_sync,
  get_status, get_file_tree

Zum Bauen (Linux):
  sudo apt install libwebkit2gtk-4.1-dev libgtk-3-dev
  cd clients/desktop && npm install && npm run tauri build

Windows/Mac: Tauri Voraussetzungen installieren, dann gleicher Befehl

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

clients/desktop/package.json

@@ -0,0 +1,22 @@
+{
+  "name": "tauri-app",
+  "private": true,
+  "version": "0.1.0",
+  "type": "module",
+  "scripts": {
+    "dev": "vite",
+    "build": "vite build",
+    "preview": "vite preview",
+    "tauri": "tauri"
+  },
+  "dependencies": {
+    "vue": "^3.5.13",
+    "@tauri-apps/api": "^2",
+    "@tauri-apps/plugin-opener": "^2"
+  },
+  "devDependencies": {
+    "@vitejs/plugin-vue": "^5.2.1",
+    "vite": "^6.0.3",
+    "@tauri-apps/cli": "^2"
+  }
+}