feat: add POST endpoint for admin marketplace import jobs

Add POST /api/v1/admin/marketplace-import-jobs endpoint to allow
admins to create import jobs for any vendor.

Changes:
- Add AdminMarketplaceImportJobRequest schema with vendor_id field
- Add create_marketplace_import_job endpoint in admin/marketplace.py
- Make vendor_code and vendor_name optional in response model
  to handle edge cases where vendor relationship may not be loaded

This fixes the 405 Method Not Allowed error when trying to import
products from the admin marketplace page.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

app/api/v1/admin/marketplace.py

@@ -10,10 +10,16 @@ from sqlalchemy.orm import Session
 
 from app.api.deps import get_current_admin_api
 from app.core.database import get_db
+from app.exceptions import VendorNotFoundException
 from app.services.admin_service import admin_service
+from app.services.marketplace_import_job_service import marketplace_import_job_service
 from app.services.stats_service import stats_service
 from models.database.user import User
-from models.schema.marketplace_import_job import MarketplaceImportJobResponse
+from models.database.vendor import Vendor
+from models.schema.marketplace_import_job import (
+    AdminMarketplaceImportJobRequest,
+    MarketplaceImportJobResponse,
+)
 
 router = APIRouter(prefix="/marketplace-import-jobs")
 logger = logging.getLogger(__name__)
@@ -40,6 +46,46 @@ def get_all_marketplace_import_jobs(
     )
 
 
+@router.post("", response_model=MarketplaceImportJobResponse)
+def create_marketplace_import_job(
+    request: AdminMarketplaceImportJobRequest,
+    db: Session = Depends(get_db),
+    current_admin: User = Depends(get_current_admin_api),
+):
+    """
+    Create a new marketplace import job (Admin only).
+
+    Admins can trigger imports for any vendor by specifying vendor_id.
+    """
+    # Look up the vendor
+    vendor = db.query(Vendor).filter(Vendor.id == request.vendor_id).first()
+    if not vendor:
+        raise VendorNotFoundException(str(request.vendor_id), identifier_type="id")
+
+    # Create the import job using the service
+    from models.schema.marketplace_import_job import MarketplaceImportJobRequest
+
+    job_request = MarketplaceImportJobRequest(
+        source_url=request.source_url,
+        marketplace=request.marketplace,
+        batch_size=request.batch_size,
+    )
+
+    job = marketplace_import_job_service.create_import_job(
+        db=db,
+        request=job_request,
+        vendor=vendor,
+        user=current_admin,
+    )
+
+    logger.info(
+        f"Admin {current_admin.username} created import job {job.id} "
+        f"for vendor {vendor.vendor_code}"
+    )
+
+    return marketplace_import_job_service.convert_to_response_model(job)
+
+
 @router.get("/stats")
 def get_import_statistics(
     db: Session = Depends(get_db),