wip: update Letzshop service and API for historical imports

- Add historical order import functionality
- Add order detail page route
- Update API endpoints for order confirmation flow

Note: These files need further updates to use the new unified order model.

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

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

app/routes/admin_pages.py

@@ -613,6 +613,30 @@ async def admin_marketplace_letzshop_page(
     )
 
 
+@router.get(
+    "/letzshop/orders/{order_id}", response_class=HTMLResponse, include_in_schema=False
+)
+async def admin_letzshop_order_detail_page(
+    request: Request,
+    order_id: int = Path(..., description="Letzshop order ID"),
+    current_user: User = Depends(get_current_admin_from_cookie_or_header),
+    db: Session = Depends(get_db),
+):
+    """
+    Render detailed Letzshop order page.
+    Shows full order information with shipping address, billing address,
+    product details, and order history.
+    """
+    return templates.TemplateResponse(
+        "admin/letzshop-order-detail.html",
+        {
+            "request": request,
+            "user": current_user,
+            "order_id": order_id,
+        },
+    )
+
+
 # ============================================================================
 # PRODUCT CATALOG ROUTES
 # ============================================================================