feat(adsb): improve ACARS/VDL2 panels with history, clear, smooth updates, and translation

- Persist ACARS/VDL2 messages across page refresh via new /acars/messages
  and /vdl2/messages endpoints backed by FlightCorrelator
- Add clear buttons to ACARS/VDL2 sidebars and right-panel datalink section
  with /acars/clear and /vdl2/clear endpoints
- Fix right-panel DATALINK MESSAGES flickering by diffing innerHTML before
  updating, with opacity transition for smooth refreshes
- Add aircraft deselect toggle (click selected aircraft again to deselect)
- Enrich VDL2 messages with ACARS label translation (label_description,
  message_type, parsed fields) matching existing ACARS translator

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

routes/acars.py

@@ -443,6 +443,26 @@ def stream_acars() -> Response:
     return response
 
 
+@acars_bp.route('/messages')
+def get_acars_messages() -> Response:
+    """Get recent ACARS messages from correlator (for history reload)."""
+    from utils.flight_correlator import get_flight_correlator
+    limit = request.args.get('limit', 50, type=int)
+    limit = max(1, min(limit, 200))
+    msgs = get_flight_correlator().get_recent_messages('acars', limit)
+    return jsonify(msgs)
+
+
+@acars_bp.route('/clear', methods=['POST'])
+def clear_acars_messages() -> Response:
+    """Clear stored ACARS messages and reset counter."""
+    global acars_message_count
+    from utils.flight_correlator import get_flight_correlator
+    get_flight_correlator().clear_acars()
+    acars_message_count = 0
+    return jsonify({'status': 'cleared'})
+
+
 @acars_bp.route('/frequencies')
 def get_frequencies() -> Response:
     """Get default ACARS frequencies."""

routes/vdl2.py

@@ -79,6 +79,22 @@ def stream_vdl2_output(process: subprocess.Popen, is_text_mode: bool = False) ->
                 data['type'] = 'vdl2'
                 data['timestamp'] = datetime.utcnow().isoformat() + 'Z'
 
+                # Enrich embedded ACARS payload with translated label
+                try:
+                    vdl2_inner = data.get('vdl2', data)
+                    acars_payload = (vdl2_inner.get('avlc') or {}).get('acars')
+                    if acars_payload and acars_payload.get('label'):
+                        from utils.acars_translator import translate_message
+                        translation = translate_message({
+                            'label': acars_payload.get('label'),
+                            'text': acars_payload.get('msg_text', ''),
+                        })
+                        acars_payload['label_description'] = translation['label_description']
+                        acars_payload['message_type'] = translation['message_type']
+                        acars_payload['parsed'] = translation['parsed']
+                except Exception:
+                    pass
+
                 # Update stats
                 vdl2_message_count += 1
                 vdl2_last_message_time = time.time()
@@ -370,6 +386,26 @@ def stream_vdl2() -> Response:
     return response
 
 
+@vdl2_bp.route('/messages')
+def get_vdl2_messages() -> Response:
+    """Get recent VDL2 messages from correlator (for history reload)."""
+    from utils.flight_correlator import get_flight_correlator
+    limit = request.args.get('limit', 50, type=int)
+    limit = max(1, min(limit, 200))
+    msgs = get_flight_correlator().get_recent_messages('vdl2', limit)
+    return jsonify(msgs)
+
+
+@vdl2_bp.route('/clear', methods=['POST'])
+def clear_vdl2_messages() -> Response:
+    """Clear stored VDL2 messages and reset counter."""
+    global vdl2_message_count
+    from utils.flight_correlator import get_flight_correlator
+    get_flight_correlator().clear_vdl2()
+    vdl2_message_count = 0
+    return jsonify({'status': 'cleared'})
+
+
 @vdl2_bp.route('/frequencies')
 def get_frequencies() -> Response:
     """Get default VDL2 frequencies."""