Implement Bodenfeuchte app: MQTT listener, SQLite storage, chart UI, Docker

- Custom Next.js server starts MQTT listener on boot
- Subscribes to zigbee2mqtt/Bodenfeuchte_1, stores soil_moisture in SQLite
- API route /api/data returns last 6 hours of measurements
- Frontend shows current value + Recharts line chart, auto-refresh every 60s
- Dockerfile + docker-compose with persistent volume for SQLite DB

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tsconfig.server.json

@@ -0,0 +1,17 @@
+{
+  "compilerOptions": {
+    "target": "ES2020",
+    "module": "commonjs",
+    "moduleResolution": "node",
+    "esModuleInterop": true,
+    "skipLibCheck": true,
+    "strict": true,
+    "outDir": "dist",
+    "rootDir": ".",
+    "paths": {
+      "@/*": ["./*"]
+    }
+  },
+  "include": ["server.ts", "lib/**/*.ts"],
+  "exclude": ["node_modules", ".next"]
+}