feat: application desktop Electron avec interface graphique complète

- Main Process spawn serveur automatiquement avec IPC sécurisé
- Dashboard temps réel : stats, utilisateurs, QR Code
- Configuration audio : devices, sample rate, bitrate, jitter buffer
- Gestion groupes : CRUD complet via API admin
- Monitoring : logs temps réel filtrables par niveau
- Notifications : toast visuelles avec auto-dismiss
- Packaging : electron-builder pour macOS (.dmg) et Linux (.deb/.AppImage)
- Documentation : README technique, QUICKSTART, CHANGELOG, guide utilisateur

Structure :
- electron/main.js (333 lignes) : Main Process + spawn serveur
- electron/preload.js (31 lignes) : IPC bridge sécurisé
- electron/ui/index.html (187 lignes) : interface dashboard
- electron/ui/styles.css (556 lignes) : dark theme
- electron/ui/app.js (626 lignes) : logic frontend

Total : 1733 lignes de code

Lancement : ./start-desktop.sh

API utilisées : /admin/stats, /admin/users, /admin/groups, /admin/config, /admin/devices/list

TODO : WebSocket VU-mètres, icônes, tray menu, graphiques monitoring

electron/package.json

@@ -0,0 +1,60 @@
+{
+  "name": "ptt-live-desktop",
+  "version": "0.3.0",
+  "description": "PTT Live - Desktop Server Application",
+  "main": "main.js",
+  "scripts": {
+    "start": "electron .",
+    "dev": "electron . --dev",
+    "build": "electron-builder",
+    "build:mac": "electron-builder --mac",
+    "build:linux": "electron-builder --linux"
+  },
+  "build": {
+    "appId": "com.pttlive.desktop",
+    "productName": "PTT Live Server",
+    "directories": {
+      "output": "dist"
+    },
+    "files": [
+      "main.js",
+      "preload.js",
+      "ui/**/*",
+      "../server/**/*",
+      "!../server/node_modules",
+      "../server/node_modules/**/*"
+    ],
+    "mac": {
+      "category": "public.app-category.utilities",
+      "icon": "assets/icon.icns",
+      "target": [
+        "dmg",
+        "zip"
+      ]
+    },
+    "linux": {
+      "category": "AudioVideo",
+      "icon": "assets/icon.png",
+      "target": [
+        "deb",
+        "AppImage"
+      ]
+    }
+  },
+  "keywords": [
+    "electron",
+    "webrtc",
+    "intercom",
+    "audio"
+  ],
+  "author": "",
+  "license": "MIT",
+  "devDependencies": {
+    "electron": "^28.0.0",
+    "electron-builder": "^24.9.1"
+  },
+  "dependencies": {
+    "electron-store": "^8.1.0",
+    "qrcode": "^1.5.4"
+  }
+}