Separate JSON API backend (vm_api.py) + React+TanStack frontend scaffold

- vm_api.py: pure FastAPI JSON API on :8098 with CORS
- vm-api.service: systemd unit for API (replaces inline HTML vm_web.py for frontend)
- vm_web.py: kept intact as fallback; Apache now proxies /api/ -> :8098
- frontend/: Vite + React + TanStack Query scaffold
- Apache vhost updated: DocumentRoot -> frontend/dist, /api/ proxy, SPA fallback
- All original HTML pages still functional via :8099 during transition

frontend/package.json

@@ -0,0 +1,24 @@
+{
+  "name": "voicemail-ui",
+  "private": true,
+  "version": "1.0.0",
+  "type": "module",
+  "scripts": {
+    "dev": "vite --port 5173",
+    "build": "tsc -b && vite build",
+    "preview": "vite preview"
+  },
+  "dependencies": {
+    "@tanstack/react-query": "^5.62.0",
+    "@tanstack/react-router": "^1.100.0",
+    "react": "^18.3.1",
+    "react-dom": "^18.3.1"
+  },
+  "devDependencies": {
+    "@types/react": "^18.3.18",
+    "@types/react-dom": "^18.3.5",
+    "@vitejs/plugin-react": "^4.3.4",
+    "typescript": "^5.6.3",
+    "vite": "^6.0.7"
+  }
+}