Fix cross-DB query: market app cart_items via data endpoint

market_context() was querying CartItem directly via g.s (db_market),
but cart_items lives in db_cart. Replace with fetch_data("cart",
"cart-items") and add the corresponding data endpoint.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

market/app.py

@@ -26,8 +26,6 @@ async def market_context() -> dict:
     from shared.infrastructure.fragments import fetch_fragments
     from shared.infrastructure.data_client import fetch_data
     from shared.contracts.dtos import CartSummaryDTO, dto_from_dict
-    from shared.models.market import CartItem
-    from sqlalchemy.orm import selectinload
 
     ctx = await base_context()
 
@@ -64,20 +62,21 @@ async def market_context() -> dict:
     ctx["auth_menu_html"] = auth_menu_html
     ctx["nav_tree_html"] = nav_tree_html
 
-    # ORM cart items for product templates (need .product relationship)
-    filters = [CartItem.deleted_at.is_(None)]
-    if ident["user_id"] is not None:
-        filters.append(CartItem.user_id == ident["user_id"])
-    elif ident["session_id"] is not None:
-        filters.append(CartItem.session_id == ident["session_id"])
+    # Cart items for product templates — fetched via internal data endpoint
+    # (cart_items table lives in db_cart, not db_market)
+    cart_items_raw = await fetch_data("cart", "cart-items", params=summary_params, required=False)
+    if cart_items_raw:
+        # Wrap as namespace objects so Jinja selectattr("product.slug", ...) works
+        from types import SimpleNamespace
+        ctx["cart"] = [
+            SimpleNamespace(
+                product=SimpleNamespace(slug=item["product_slug"]),
+                quantity=item["quantity"],
+            )
+            for item in cart_items_raw
+        ]
     else:
         ctx["cart"] = []
-        return ctx
-
-    result = await g.s.execute(
-        select(CartItem).where(*filters).options(selectinload(CartItem.product))
-    )
-    ctx["cart"] = list(result.scalars().all())
 
     return ctx