Node database: collect nodes during sync, expose GET /api/nodes (#7)

README.md

@@ -28,6 +28,8 @@ All API endpoints live under the `/api` prefix:
 - `GET /api/status` — `{ connected, myNodeNum, host, port }`
 - `POST /api/send` — body `{ "text": "...", "to"?: <node number | "!b" | "broadcast"> }`, returns `{ id }`
 - `GET /api/channels` — the device's Meshtastic channels as `{ index, name, uplinkEnabled, downlinkEnabled }[]` (psk/keys are redacted; empty until the initial sync completes)
+- `GET /api/nodes` — known mesh nodes as `{ num, longName?, shortName?, hwModel?, batteryLevel?, lastHeard: number|null, position?: { lat, lon, alt? } }[]`, sorted by node number. Collected during the initial sync plus live position updates; names/hwModel/battery appear only when reported, `lastHeard` is epoch seconds (null = never heard), and `position` only when both coordinates are known
+- `GET /api/nodes/:id` — one node looked up by exact node number (numbers or numeric strings), then case-insensitive exact long/short name, else the unique case-insensitive substring match; 404 when nothing or more than one node matches
 
 Interactive API docs (Scalar) are served at `/`, with the OpenAPI JSON at
 `/docs-json`.
@@ -37,6 +39,8 @@ curl http://localhost:3000/api/status
 curl -X POST http://localhost:3000/api/send -H 'content-type: application/json' -d '{"text":"hi"}'
 curl -X POST http://localhost:3000/api/send -H 'content-type: application/json' -d '{"to":123456789,"text":"hello"}'
 curl http://localhost:3000/api/channels
+curl http://localhost:3000/api/nodes
+curl http://localhost:3000/api/nodes/kamil
 ```
 
 `to` omitted, `"!b"`, or `"broadcast"` sends to the broadcast address `0xffffffff`.