Phase A: generierter Dart-Client + DI-Foundation für Rust-Backend

OpenAPI-Generator-Setup:
- tool/generate_api_client.sh: Direkter Aufruf der openapi-generator-cli.jar
  (Java-CLI statt Dart-build_runner-Integration — vermeidet die
  analyzer-/source_gen-Version-Hölle mit json_serializable)
- tool/fetch_openapi_generator.sh: lädt die JAR (29 MB) nach (gitignored)
- openapi/holzleitner.json: Snapshot der Backend-Spec für reproduzierbare
  Generation
- packages/holzleitner_api/: generiertes Dart-Sub-Package (built_value +
  dio), per path-dep im Haupt-pubspec eingehängt

Netzwerk-Layer (lib/data/network/):
- BackendConfig: API- und Keycloak-Endpoints für Local-Dev (localhost
  wegen Keycloak-iss-Claim).
- AuthTokenProvider-Schnittstelle.
- DevPasswordGrantTokenProvider: Phase-A-Provider via Keycloak
  password-grant, Token-Caching mit Expiry-Check (Phase B ersetzt das
  durch flutter_appauth PKCE).
- HolzleitnerAuthInterceptor: dynamischer Bearer-Inject pro Request.
- HolzleitnerApiFactory: baut die generierte HolzleitnerApi-Klasse
  mit unserem Interceptor statt der vier Default-Auth-Interceptors.
- network_locator.registerNetworking(): get_it-Setup, in main() vor
  runApp() aufgerufen.

Clean-Arch-Scaffolding (lib/data/, lib/domain/):
- Verzeichnisstruktur für Phase C+D angelegt (mapper/, repository/,
  entity/, repository/) — befüllt sich in den Folge-Phasen.

Smoke-Test:
- tool/smoke_test_api.dart ruft /health (ungeschützt) und /me/cars
  (mit Bearer) via generiertem Client — grün gegen lokales Backend.

packages/holzleitner_api/lib/src/model/car.g.dart

@@ -0,0 +1,130 @@
+// GENERATED CODE - DO NOT MODIFY BY HAND
+
+part of 'car.dart';
+
+// **************************************************************************
+// BuiltValueGenerator
+// **************************************************************************
+
+class _$Car extends Car {
+  @override
+  final int accountId;
+  @override
+  final bool active;
+  @override
+  final String id;
+  @override
+  final String plate;
+
+  factory _$Car([void Function(CarBuilder)? updates]) =>
+      (CarBuilder()..update(updates))._build();
+
+  _$Car._(
+      {required this.accountId,
+      required this.active,
+      required this.id,
+      required this.plate})
+      : super._();
+  @override
+  Car rebuild(void Function(CarBuilder) updates) =>
+      (toBuilder()..update(updates)).build();
+
+  @override
+  CarBuilder toBuilder() => CarBuilder()..replace(this);
+
+  @override
+  bool operator ==(Object other) {
+    if (identical(other, this)) return true;
+    return other is Car &&
+        accountId == other.accountId &&
+        active == other.active &&
+        id == other.id &&
+        plate == other.plate;
+  }
+
+  @override
+  int get hashCode {
+    var _$hash = 0;
+    _$hash = $jc(_$hash, accountId.hashCode);
+    _$hash = $jc(_$hash, active.hashCode);
+    _$hash = $jc(_$hash, id.hashCode);
+    _$hash = $jc(_$hash, plate.hashCode);
+    _$hash = $jf(_$hash);
+    return _$hash;
+  }
+
+  @override
+  String toString() {
+    return (newBuiltValueToStringHelper(r'Car')
+          ..add('accountId', accountId)
+          ..add('active', active)
+          ..add('id', id)
+          ..add('plate', plate))
+        .toString();
+  }
+}
+
+class CarBuilder implements Builder<Car, CarBuilder> {
+  _$Car? _$v;
+
+  int? _accountId;
+  int? get accountId => _$this._accountId;
+  set accountId(int? accountId) => _$this._accountId = accountId;
+
+  bool? _active;
+  bool? get active => _$this._active;
+  set active(bool? active) => _$this._active = active;
+
+  String? _id;
+  String? get id => _$this._id;
+  set id(String? id) => _$this._id = id;
+
+  String? _plate;
+  String? get plate => _$this._plate;
+  set plate(String? plate) => _$this._plate = plate;
+
+  CarBuilder() {
+    Car._defaults(this);
+  }
+
+  CarBuilder get _$this {
+    final $v = _$v;
+    if ($v != null) {
+      _accountId = $v.accountId;
+      _active = $v.active;
+      _id = $v.id;
+      _plate = $v.plate;
+      _$v = null;
+    }
+    return this;
+  }
+
+  @override
+  void replace(Car other) {
+    _$v = other as _$Car;
+  }
+
+  @override
+  void update(void Function(CarBuilder)? updates) {
+    if (updates != null) updates(this);
+  }
+
+  @override
+  Car build() => _build();
+
+  _$Car _build() {
+    final _$result = _$v ??
+        _$Car._(
+          accountId: BuiltValueNullFieldError.checkNotNull(
+              accountId, r'Car', 'accountId'),
+          active:
+              BuiltValueNullFieldError.checkNotNull(active, r'Car', 'active'),
+          id: BuiltValueNullFieldError.checkNotNull(id, r'Car', 'id'),
+          plate: BuiltValueNullFieldError.checkNotNull(plate, r'Car', 'plate'),
+        );
+    replace(_$result);
+    return _$result;
+  }
+}
+
+// ignore_for_file: deprecated_member_use_from_same_package,type=lint