FEAT: Plugin Manager folder picker + scan dirs (Windows/macOS), docker .env paths, status bar adaptive tips, DSP Tool vao sub-tab audioclip

- Plugins Manager (Tools menu): Browse folder (Tauri dialog + fallback paste path), Save & Scan VST/SoundFont dirs -> plugin_dirs.json (user override, env la base)
- Docker: VST_DIR/SOUNDFONT_DIR/PIANOBK_DIR tu .env/docker-compose mount vao container + env cho engine/celery
- Status bar: bo label 'Scroll: Zoom' -> Adaptive tips (prHint + fallback text)
- DSP Tool: move vao SUB-TAB editor audioclip (Phase Inv / Swap L/R / Reverse + apply vung chon/ca clip)
- Tauri: them tauri-plugin-dialog + dialog:default permission cho folder picker

src-tauri/tauri.conf.json

@@ -8,6 +8,7 @@
     "devUrl": "http://localhost:8000"
   },
   "app": {
+    "withGlobalTauri": true,
     "windows": [
       {
         "title": "Sonic Forge DAW - Professional Desktop Studio",