feat: add Letzshop CSV product export for admin and vendor

- Create letzshop_export_service.py with CSV generation logic
- Add admin endpoint: GET /api/v1/admin/vendors/{vendor}/export/letzshop
- Add vendor endpoint: GET /api/v1/vendor/letzshop/export
- Support language selection (en, fr, de) and include_inactive filter
- Generate Google Shopping compatible tab-delimited CSV format
- Add comprehensive integration tests for both endpoints

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/api/v1/admin/vendors.py

@@ -308,3 +308,56 @@ def delete_vendor(
     message = admin_service.delete_vendor(db, vendor.id)
     db.commit()
     return {"message": message}
+
+
+# ============================================================================
+# LETZSHOP EXPORT
+# ============================================================================
+
+
+@router.get("/{vendor_identifier}/export/letzshop")
+def export_vendor_products_letzshop(
+    vendor_identifier: str = Path(..., description="Vendor ID or vendor_code"),
+    language: str = Query("en", description="Language for title/description (en, fr, de)"),
+    include_inactive: bool = Query(False, description="Include inactive products"),
+    db: Session = Depends(get_db),
+    current_admin: User = Depends(get_current_admin_api),
+):
+    """
+    Export vendor products in Letzshop CSV format (Admin only).
+
+    Generates a Google Shopping compatible CSV file for Letzshop marketplace.
+    The file uses tab-separated values and includes all required Letzshop fields.
+
+    **Supported languages:** en, fr, de
+
+    **CSV Format:**
+    - Delimiter: Tab (\\t)
+    - Encoding: UTF-8
+    - Fields: id, title, description, price, availability, image_link, etc.
+
+    Returns:
+        CSV file as attachment (vendor_code_letzshop_export.csv)
+    """
+    from fastapi.responses import Response
+
+    from app.services.letzshop_export_service import letzshop_export_service
+
+    vendor = vendor_service.get_vendor_by_identifier(db, vendor_identifier)
+
+    csv_content = letzshop_export_service.export_vendor_products(
+        db=db,
+        vendor_id=vendor.id,
+        language=language,
+        include_inactive=include_inactive,
+    )
+
+    filename = f"{vendor.vendor_code.lower()}_letzshop_export.csv"
+
+    return Response(
+        content=csv_content,
+        media_type="text/csv; charset=utf-8",
+        headers={
+            "Content-Disposition": f'attachment; filename="{filename}"',
+        },
+    )

app/api/v1/vendor/letzshop.py

@@ -690,3 +690,57 @@ def list_fulfillment_queue(
         skip=skip,
         limit=limit,
     )
+
+
+# ============================================================================
+# Product Export
+# ============================================================================
+
+
+@router.get("/export")
+def export_products_letzshop(
+    language: str = Query("en", description="Language for title/description (en, fr, de)"),
+    include_inactive: bool = Query(False, description="Include inactive products"),
+    current_user: User = Depends(get_current_vendor_api),
+    db: Session = Depends(get_db),
+):
+    """
+    Export vendor products in Letzshop CSV format.
+
+    Generates a Google Shopping compatible CSV file for Letzshop marketplace.
+    The file uses tab-separated values and includes all required Letzshop fields.
+
+    **Supported languages:** en, fr, de
+
+    **CSV Format:**
+    - Delimiter: Tab (\\t)
+    - Encoding: UTF-8
+    - Fields: id, title, description, price, availability, image_link, etc.
+
+    Returns:
+        CSV file as attachment (vendor_code_letzshop_export.csv)
+    """
+    from fastapi.responses import Response
+
+    from app.services.letzshop_export_service import letzshop_export_service
+    from app.services.vendor_service import vendor_service
+
+    vendor_id = current_user.token_vendor_id
+    vendor = vendor_service.get_vendor_by_id(db, vendor_id)
+
+    csv_content = letzshop_export_service.export_vendor_products(
+        db=db,
+        vendor_id=vendor_id,
+        language=language,
+        include_inactive=include_inactive,
+    )
+
+    filename = f"{vendor.vendor_code.lower()}_letzshop_export.csv"
+
+    return Response(
+        content=csv_content,
+        media_type="text/csv; charset=utf-8",
+        headers={
+            "Content-Disposition": f'attachment; filename="{filename}"',
+        },
+    )