feat(T02): vehicle management + mobile.de push + vehicle UI

- Vehicle model: 25+ fields, 5 vehicle types, soft-delete
- Vehicle CRUD: 7 API endpoints with JWT auth, filter/sort/paginate
- mobile.de: push/update/delete listings, field mapping, retry logic
- MobileDeListing model for sync status tracking
- Frontend: VehicleList, VehicleForm, VehicleDetail, MobileDeStatus
- 73 backend tests (82% coverage), 16 frontend tests

frontend/lib/vehicles.ts

@@ -0,0 +1,149 @@
+import { apiFetch, type PaginatedResponse } from './api';
+
+export interface VehicleResponse {
+  id: string;
+  make: string;
+  model: string;
+  fin: string;
+  year?: number;
+  first_registration?: string;
+  power_kw?: number;
+  power_hp?: number;
+  fuel_type?: string;
+  transmission?: string;
+  color?: string;
+  condition: string;
+  location?: string;
+  availability: string;
+  price: number;
+  vehicle_type: string;
+  lkw_type?: string;
+  machine_type?: string;
+  body_type?: string;
+  operating_hours?: number;
+  operating_hours_unit?: string;
+  mileage_km?: number;
+  description?: string;
+  created_at?: string;
+  updated_at?: string;
+  deleted_at?: string | null;
+}
+
+export interface VehicleCreateData {
+  make: string;
+  model: string;
+  fin: string;
+  year?: number;
+  first_registration?: string;
+  power_kw?: number;
+  fuel_type?: string;
+  transmission?: string;
+  color?: string;
+  condition?: string;
+  location?: string;
+  availability?: string;
+  price: number;
+  vehicle_type: string;
+  lkw_type?: string;
+  machine_type?: string;
+  body_type?: string;
+  operating_hours?: number;
+  operating_hours_unit?: string;
+  mileage_km?: number;
+  description?: string;
+}
+
+export interface VehicleUpdateData {
+  make?: string;
+  model?: string;
+  fin?: string;
+  year?: number;
+  first_registration?: string;
+  power_kw?: number;
+  fuel_type?: string;
+  transmission?: string;
+  color?: string;
+  condition?: string;
+  location?: string;
+  availability?: string;
+  price?: number;
+  vehicle_type?: string;
+  lkw_type?: string;
+  machine_type?: string;
+  body_type?: string;
+  operating_hours?: number;
+  operating_hours_unit?: string;
+  mileage_km?: number;
+  description?: string;
+}
+
+export interface VehicleListParams {
+  page?: number;
+  page_size?: number;
+  type?: string;
+  availability?: string;
+  min_price?: number;
+  max_price?: number;
+  search?: string;
+  sort?: string;
+}
+
+export interface MobileDeStatusResponse {
+  synced: boolean;
+  ad_id?: string;
+  synced_at?: string;
+  sync_status: string;
+  error_log?: string;
+}
+
+export interface MobileDePushResponse {
+  message: string;
+  vehicle_id: string;
+  listing_id?: string;
+}
+
+export async function listVehicles(params: VehicleListParams = {}): Promise<PaginatedResponse<VehicleResponse>> {
+  const query = new URLSearchParams();
+  if (params.page) query.set('page', String(params.page));
+  if (params.page_size) query.set('page_size', String(params.page_size));
+  if (params.type) query.set('type', params.type);
+  if (params.availability) query.set('availability', params.availability);
+  if (params.min_price !== undefined) query.set('min_price', String(params.min_price));
+  if (params.max_price !== undefined) query.set('max_price', String(params.max_price));
+  if (params.search) query.set('search', params.search);
+  if (params.sort) query.set('sort', params.sort);
+  const qs = query.toString();
+  return apiFetch<PaginatedResponse<VehicleResponse>>(`/vehicles/${qs ? `?${qs}` : ''}`);
+}
+
+export async function getVehicle(id: string): Promise<VehicleResponse> {
+  return apiFetch<VehicleResponse>(`/vehicles/${id}`);
+}
+
+export async function createVehicle(data: VehicleCreateData): Promise<VehicleResponse> {
+  return apiFetch<VehicleResponse>('/vehicles/', {
+    method: 'POST',
+    body: JSON.stringify(data),
+  });
+}
+
+export async function updateVehicle(id: string, data: VehicleUpdateData): Promise<VehicleResponse> {
+  return apiFetch<VehicleResponse>(`/vehicles/${id}`, {
+    method: 'PUT',
+    body: JSON.stringify(data),
+  });
+}
+
+export async function deleteVehicle(id: string): Promise<VehicleResponse> {
+  return apiFetch<VehicleResponse>(`/vehicles/${id}`, { method: 'DELETE' });
+}
+
+export async function pushToMobileDe(vehicleId: string): Promise<MobileDePushResponse> {
+  return apiFetch<MobileDePushResponse>(`/vehicles/${vehicleId}/mobile-de/push`, {
+    method: 'POST',
+  });
+}
+
+export async function getMobileDeStatus(vehicleId: string): Promise<MobileDeStatusResponse> {
+  return apiFetch<MobileDeStatusResponse>(`/vehicles/${vehicleId}/mobile-de/status`);
+}