fix(07): WR-05 add 5 MB file size limit to CSV vehicle import endpoint

FileInterceptor used multer's default memory storage with no size limit.
An oversized file could exhaust Node.js heap before parsing begins.
Add fileSize: 5*1024*1024 (5 MB) — sufficient for any realistic vehicle list.

apps/api/src/dkv/dkv.controller.ts

@@ -206,7 +206,9 @@ export class DkvController {
    */
   @Post('vehicles/import')
   @Roles(Role.ADMIN, Role.SUPER_ADMIN)
-  @UseInterceptors(FileInterceptor('file'))
+  @UseInterceptors(FileInterceptor('file', {
+    limits: { fileSize: 5 * 1024 * 1024 }, // 5 MB — generous for any realistic vehicle list (WR-05)
+  }))
   async importVehicles(
     @Req() req: any,
     @UploadedFile() file: any,