refactor: move LetzshopExportRequest to schema layer

Follows architecture rule: Pydantic schemas belong in models/schema/

- Moved LetzshopExportRequest to models/schema/vendor.py
- Added LetzshopExportFileInfo and LetzshopExportResponse schemas
- Updated API endpoint to use proper response_model
- Removed inline BaseModel import from API file

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

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

models/schema/vendor.py

@@ -293,3 +293,37 @@ class VendorSummary(BaseModel):
 # NOTE: Vendor ownership transfer schemas have been removed.
 # Ownership transfer is now handled at the Company level.
 # See models/schema/company.py for CompanyTransferOwnership and CompanyTransferOwnershipResponse.
+
+
+# ============================================================================
+# LETZSHOP EXPORT SCHEMAS
+# ============================================================================
+
+
+class LetzshopExportRequest(BaseModel):
+    """Request body for Letzshop export to pickup folder."""
+
+    include_inactive: bool = Field(
+        default=False,
+        description="Include inactive products in export"
+    )
+
+
+class LetzshopExportFileInfo(BaseModel):
+    """Info about an exported file."""
+
+    language: str
+    filename: str | None = None
+    path: str | None = None
+    size_bytes: int | None = None
+    error: str | None = None
+
+
+class LetzshopExportResponse(BaseModel):
+    """Response from Letzshop export to folder."""
+
+    success: bool
+    message: str
+    vendor_code: str
+    export_directory: str
+    files: list[LetzshopExportFileInfo]