Fix inconsistent cart count: include calendar entries in market app

Market context processor was only counting product CartItems for cart_count,
while blog/cart/events apps include calendar entries too. Use cart service
for consistent counts across all apps.

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

app.py

@@ -18,10 +18,12 @@ async def market_context() -> dict:
     Market app context processor.
 
     - menu_items: direct DB query
-    - cart/cart_count/cart_total: direct DB (market owns CartItem/Product)
+    - cart_count/cart_total: via cart service (includes calendar entries)
+    - cart: direct ORM query (templates need .product relationship)
     """
     from shared.infrastructure.context import base_context
     from shared.services.navigation import get_navigation_tree
+    from shared.services.registry import services
     from shared.infrastructure.cart_identity import current_cart_identity
     from shared.models.market import CartItem
     from sqlalchemy.orm import selectinload
@@ -30,30 +32,29 @@ async def market_context() -> dict:
 
     ctx["menu_items"] = await get_navigation_tree(g.s)
 
-    # Market owns CartItem/Product — query directly for template compat
     ident = current_cart_identity()
+
+    # cart_count/cart_total via service (consistent with blog/events apps)
+    summary = await services.cart.cart_summary(
+        g.s, user_id=ident["user_id"], session_id=ident["session_id"],
+    )
+    ctx["cart_count"] = summary.count + summary.calendar_count
+    ctx["cart_total"] = float(summary.total + summary.calendar_total)
+
+    # ORM cart items for product templates (need .product relationship)
     filters = [CartItem.deleted_at.is_(None)]
-    if ident["user_id"]:
+    if ident["user_id"] is not None:
         filters.append(CartItem.user_id == ident["user_id"])
-    elif ident["session_id"]:
+    elif ident["session_id"] is not None:
         filters.append(CartItem.session_id == ident["session_id"])
     else:
         ctx["cart"] = []
-        ctx["cart_count"] = 0
-        ctx["cart_total"] = 0
         return ctx
 
     result = await g.s.execute(
         select(CartItem).where(*filters).options(selectinload(CartItem.product))
     )
-    cart_items = list(result.scalars().all())
+    ctx["cart"] = list(result.scalars().all())
-
-    ctx["cart"] = cart_items
-    ctx["cart_count"] = sum(ci.quantity for ci in cart_items)
-    ctx["cart_total"] = float(sum(
-        (ci.product.special_price or ci.product.regular_price or 0) * ci.quantity
-        for ci in cart_items if ci.product
-    ))
 
     return ctx