fix(ui): refresh Contact Info path display in real-time

Path info in Contact Info modal was stale due to 60s server cache
and no refresh after path operations. Now:
- Invalidate contacts cache after reset_path, change_path, path_update
- Emit 'path_changed' socket event on PATH_UPDATE from device
- UI listens and re-renders Contact Info when path changes
- Reset to FLOOD button immediately refreshes the path display

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

app/routes/api.py

@@ -2322,6 +2322,7 @@ def reset_contact_to_flood(pubkey):
         dev_result = dm.reset_path(pubkey)
         logger.info(f"reset_path({pubkey[:12]}...) result: {dev_result}")
         if dev_result.get('success'):
+            invalidate_contacts_cache()
             return jsonify({'success': True}), 200
         return jsonify({'success': False, 'error': dev_result.get('error', 'Device reset failed')}), 500
     except Exception as e: