Optional router-level API key that gates router/API/web UI access (leave empty to disable)
## Supplying the router API key
If you set `nomyo-router-api-key` in `config.yaml` (or `NOMYO_ROUTER_API_KEY` env), every request to NOMYO Router must include the key:
- HTTP header (recommended): `Authorization: Bearer <router_key>`
- Query param (fallback): `?api_key=<router_key>`
Examples:
```bash
curl -H "Authorization: Bearer $NOMYO_ROUTER_API_KEY" http://localhost:12434/api/tags
curl "http://localhost:12434/api/tags?api_key=$NOMYO_ROUTER_API_KEY"
```
