Render cart-mini directly in add-to-cart HTMX response

The handler already has g.cart with the updated items — no need to
make an HTTP round-trip to the cart app's fragment endpoint. Renders
the _mini.html macro directly with the count from g.cart.

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

bp/product/routes.py

@@ -254,23 +254,8 @@ def register():
 
         # htmx response: OOB-swap mini cart + product buttons
         if request.headers.get("HX-Request") == "true":
-            # Commit so the cart app sees the updated data when we fetch the fragment
-            await g.tx.commit()
-            g.tx = await g.s.begin()
-
-            from shared.infrastructure.fragments import fetch_fragment
-            from shared.infrastructure.cart_identity import current_cart_identity as _ci
-            frag_ident = _ci()
-            cart_params = {}
-            if frag_ident["user_id"] is not None:
-                cart_params["user_id"] = frag_ident["user_id"]
-            if frag_ident["session_id"] is not None:
-                cart_params["session_id"] = frag_ident["session_id"]
-            cart_mini_html = await fetch_fragment("cart", "cart-mini", params=cart_params)
-
             return await render_template(
                 "_types/product/_added.html",
-                cart_mini_html=cart_mini_html,
                 cart=g.cart,
                 item=ci,
             )