feat(acars): add message translator and ADS-B datalink integration

Add ACARS label translation, message classification, and field parsers
so decoded messages show human-readable descriptions instead of raw
label codes (H1, DF, _d, 5Z, etc.). Integrate translated ACARS
messages into the ADS-B aircraft detail panel and add a live message
feed to the standalone ACARS mode.

- New utils/acars_translator.py with ~50 label codes, type classifier,
  and parsers for position reports, engine data, weather, and OOOI
- Enrich messages at ingest in routes/acars.py with translation fields
- Backfill translation in /adsb/aircraft/<icao>/messages endpoint
- ADS-B dashboard: DATALINK MESSAGES section in aircraft detail panel
  with auto-refresh, color-coded type badges, and parsed field display
- Standalone ACARS mode: scrollable live message feed (max 30 cards)
- Fix default N. America ACARS frequencies to 131.550/130.025/129.125
- Unit tests covering all translator functions

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

routes/acars.py

@@ -21,7 +21,7 @@ import app as app_module
 from utils.logging import sensor_logger as logger
 from utils.validation import validate_device_index, validate_gain, validate_ppm
 from utils.sdr import SDRFactory, SDRType
-from utils.sse import sse_stream_fanout
+from utils.sse import sse_stream_fanout
 from utils.event_pipeline import process_event
 from utils.constants import (
     PROCESS_TERMINATE_TIMEOUT,
@@ -33,10 +33,11 @@ from utils.process import register_process, unregister_process
 
 acars_bp = Blueprint('acars', __name__, url_prefix='/acars')
 
-# Default VHF ACARS frequencies (MHz) - common worldwide
+# Default VHF ACARS frequencies (MHz) - North America primary
 DEFAULT_ACARS_FREQUENCIES = [
-    '131.725',  # North America
-    '131.825',  # North America
+    '131.550',  # North America primary
+    '130.025',  # North America secondary
+    '129.125',  # North America tertiary
 ]
 
 # Message counter for statistics
@@ -120,6 +121,16 @@ def stream_acars_output(process: subprocess.Popen, is_text_mode: bool = False) -
                 data['type'] = 'acars'
                 data['timestamp'] = datetime.utcnow().isoformat() + 'Z'
 
+                # Enrich with translated label and parsed fields
+                try:
+                    from utils.acars_translator import translate_message
+                    translation = translate_message(data)
+                    data['label_description'] = translation['label_description']
+                    data['message_type'] = translation['message_type']
+                    data['parsed'] = translation['parsed']
+                except Exception:
+                    pass
+
                 # Update stats
                 acars_message_count += 1
                 acars_last_message_time = time.time()
@@ -411,25 +422,25 @@ def stop_acars() -> Response:
     return jsonify({'status': 'stopped'})
 
 
-@acars_bp.route('/stream')
-def stream_acars() -> Response:
-    """SSE stream for ACARS messages."""
-    def _on_msg(msg: dict[str, Any]) -> None:
-        process_event('acars', msg, msg.get('type'))
-
-    response = Response(
-        sse_stream_fanout(
-            source_queue=app_module.acars_queue,
-            channel_key='acars',
-            timeout=SSE_QUEUE_TIMEOUT,
-            keepalive_interval=SSE_KEEPALIVE_INTERVAL,
-            on_message=_on_msg,
-        ),
-        mimetype='text/event-stream',
-    )
-    response.headers['Cache-Control'] = 'no-cache'
-    response.headers['X-Accel-Buffering'] = 'no'
-    return response
+@acars_bp.route('/stream')
+def stream_acars() -> Response:
+    """SSE stream for ACARS messages."""
+    def _on_msg(msg: dict[str, Any]) -> None:
+        process_event('acars', msg, msg.get('type'))
+
+    response = Response(
+        sse_stream_fanout(
+            source_queue=app_module.acars_queue,
+            channel_key='acars',
+            timeout=SSE_QUEUE_TIMEOUT,
+            keepalive_interval=SSE_KEEPALIVE_INTERVAL,
+            on_message=_on_msg,
+        ),
+        mimetype='text/event-stream',
+    )
+    response.headers['Cache-Control'] = 'no-cache'
+    response.headers['X-Accel-Buffering'] = 'no'
+    return response
 
 
 @acars_bp.route('/frequencies')
@@ -438,7 +449,7 @@ def get_frequencies() -> Response:
     return jsonify({
         'default': DEFAULT_ACARS_FREQUENCIES,
         'regions': {
-            'north_america': ['131.725', '131.825'],
+            'north_america': ['131.550', '130.025', '129.125'],
             'europe': ['131.525', '131.725', '131.550'],
             'asia_pacific': ['131.550', '131.450'],
         }

routes/adsb.py

@@ -1189,4 +1189,17 @@ def get_aircraft_messages(icao: str):
 
     from utils.flight_correlator import get_flight_correlator
     messages = get_flight_correlator().get_messages_for_aircraft(icao=icao.upper(), callsign=callsign)
+
+    # Backfill translation on messages missing label_description
+    try:
+        from utils.acars_translator import translate_message
+        for msg in messages.get('acars', []):
+            if not msg.get('label_description'):
+                translation = translate_message(msg)
+                msg['label_description'] = translation['label_description']
+                msg['message_type'] = translation['message_type']
+                msg['parsed'] = translation['parsed']
+    except Exception:
+        pass
+
     return jsonify({'status': 'success', 'icao': icao.upper(), **messages})