feat(geocode): fully offline reverse geocode via local Pi API

- Remove all Nominatim/external calls from frontend
- Add /api/geocode?lat=&lon= route using reverse_geocoder (20MB offline KD-tree)
- JS hits /api/geocode only — works with no internet at all
- Falls back to raw coords if Pi route fails
- Add reverse_geocoder to requirements.txt

Co-authored-by: Copilot <[email protected]>

app.py

@@ -89,6 +89,23 @@ def trip_route(trip_id):
         return jsonify(error=f"Trip not found: {trip_id}"), 404
     return jsonify(trip)
 
+@app.route('/api/geocode')
+def geocode_route():
+    try:
+        lat = float(request.args['lat'])
+        lon = float(request.args['lon'])
+    except (KeyError, ValueError):
+        return jsonify(error="lat and lon required"), 400
+    import reverse_geocoder as rg
+    results = rg.search([(lat, lon)], mode=1, verbose=False)
+    if results:
+        r = results[0]
+        parts = [r.get('name', ''), r.get('admin1', '')]
+        label = ', '.join(p for p in parts if p)
+    else:
+        label = f"{lat:.5f}, {lon:.5f}"
+    return jsonify(label=label)
+
 @app.route('/api/dash/devices')
 def dash_devices():
     devices = app_dash.list_usb_storage_partitions()