Adaptive Positionsmeldung nach Bewegungszustand

- TrackState-Zustände (no_fix/static/moving_slow/moving_medium/moving_fast)
  mit je eigenem Meldeintervall mit/ohne Auftrag (lib/tools/track_state.dart)
- Festes Sampling (15s) statt fixem 120s-Timer; Sofortmeldung bei
  Zustandswechsel, sonst nach Zustandsintervall (mqtt_core.dart)
- track-JSON um state (String) und speed (m/s) erweitert
- Statisch-Erkennung über GPS-Genauigkeit, aktiver Auftrag = akzeptiert
  und <=15min vor ordertime
- chat_message.dart: Direktimport von objectbox.dart ergaenzt, behebt
  build_runner-Aufloesungsfehler (ChatMessage-Entity)
- Release-Build-Script (build_release_apk.sh)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

lib/network_messages/track_message.dart

@@ -12,6 +12,12 @@ class TrackPosition {
 
   late int acc;
 
+  /// Bewegungszustand der Ortung (String-Label, z. B. "static", "moving_medium").
+  late String state;
+
+  /// Geschwindigkeit in m/s.
+  late double speed;
+
   TrackPosition();
 
   factory TrackPosition.fromJson(Map<String, dynamic> json) => _$TrackPositionFromJson(json);

lib/network_messages/track_message.g.dart

@@ -11,7 +11,9 @@ TrackPosition _$TrackPositionFromJson(Map<String, dynamic> json) =>
       ..time = (json['time'] as num).toInt()
       ..lat = (json['lat'] as num).toDouble()
       ..long = (json['long'] as num).toDouble()
-      ..acc = (json['acc'] as num).toInt();
+      ..acc = (json['acc'] as num).toInt()
+      ..state = json['state'] as String
+      ..speed = (json['speed'] as num).toDouble();
 
 Map<String, dynamic> _$TrackPositionToJson(TrackPosition instance) =>
     <String, dynamic>{
@@ -19,4 +21,6 @@ Map<String, dynamic> _$TrackPositionToJson(TrackPosition instance) =>
       'lat': instance.lat,
       'long': instance.long,
       'acc': instance.acc,
+      'state': instance.state,
+      'speed': instance.speed,
     };