Fix cart template cross-app url_for crash and favicon 404

- Cart _cart.html: replace url_for('market.browse.product...') with
  market_product_url() for links and cart_global.update_quantity for
  quantity forms (market endpoints don't exist in cart app)
- Factory favicon route: use STATIC_DIR instead of relative "static"
  (resolves to shared/static/ where favicon.ico actually lives)
- Cart context processor: fetch all 3 fragments (cart-mini, auth-menu,
  nav-tree) concurrently, matching pattern in all other apps

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

cart/app.py

@@ -52,17 +52,32 @@ async def cart_context() -> dict:
     """
     from shared.infrastructure.context import base_context
     from shared.services.navigation import get_navigation_tree
-    from shared.infrastructure.fragments import fetch_fragment
+    from shared.infrastructure.cart_identity import current_cart_identity
+    from shared.infrastructure.fragments import fetch_fragments
 
     ctx = await base_context()
 
-    ctx["nav_tree_html"] = await fetch_fragment(
-        "blog", "nav-tree",
-        params={"app_name": "cart", "path": request.path},
-    )
     # Fallback for _nav.html when nav-tree fragment fetch fails
     ctx["menu_items"] = await get_navigation_tree(g.s)
 
+    # Pre-fetch cross-app HTML fragments concurrently
+    user = getattr(g, "user", None)
+    ident = current_cart_identity()
+    cart_params = {}
+    if ident["user_id"] is not None:
+        cart_params["user_id"] = ident["user_id"]
+    if ident["session_id"] is not None:
+        cart_params["session_id"] = ident["session_id"]
+
+    cart_mini_html, auth_menu_html, nav_tree_html = await fetch_fragments([
+        ("cart", "cart-mini", cart_params or None),
+        ("account", "auth-menu", {"email": user.email} if user else None),
+        ("blog", "nav-tree", {"app_name": "cart", "path": request.path}),
+    ])
+    ctx["cart_mini_html"] = cart_mini_html
+    ctx["auth_menu_html"] = auth_menu_html
+    ctx["nav_tree_html"] = nav_tree_html
+
     # Cart app owns cart data — use g.cart from _load_cart
     all_cart = getattr(g, "cart", None) or []
     all_cal = await get_calendar_cart_entries(g.s)

cart/templates/_types/product/_cart.html

@@ -130,7 +130,7 @@
         class="w-24 h-24 sm:w-32 sm:h-28 rounded-xl border border-dashed border-stone-300 flex items-center justify-center text-xs text-stone-400"
       >
         No image
-      </div>'market', 'product', p.slug
+      </div>
     {% endif %}
   </div>
 
@@ -139,7 +139,7 @@
       <div class="flex flex-col sm:flex-row sm:items-start justify-between gap-2 sm:gap-3">
         <div class="min-w-0">
           <h2 class="text-sm sm:text-base md:text-lg font-semibold text-stone-900">
-            {% set href=url_for('market.browse.product.product_detail', product_slug=p.slug) %}
+            {% set href=market_product_url(p.slug) %}
             <a
               href="{{ href }}"
               hx_get="{{href}}"
@@ -188,12 +188,12 @@
       <div class="mt-3 flex flex-col sm:flex-row sm:items-center justify-between gap-2 sm:gap-4">
         <div class="flex items-center gap-2 text-xs sm:text-sm text-stone-700">
           <span class="text-[0.65rem] sm:text-xs uppercase tracking-wide text-stone-500">Quantity</span>
+          {% set qty_url = url_for('cart_global.update_quantity', product_id=p.id) %}
           <form
-            action="{{ url_for('market.browse.product.cart', product_slug=p.slug) }}"
+            action="{{ qty_url }}"
             method="post"
-            hx-post="{{ url_for('market.browse.product.cart', product_slug=p.slug) }}"
-            hx-target="#cart-mini"
-            hx-swap="outerHTML"
+            hx-post="{{ qty_url }}"
+            hx-swap="none"
           >
             <input type="hidden" name="csrf_token" value="{{ csrf_token() }}">
             <input
@@ -212,11 +212,10 @@
             {{ item.quantity }}
           </span>
           <form
-            action="{{ url_for('market.browse.product.cart', product_slug=p.slug) }}"
+            action="{{ qty_url }}"
             method="post"
-            hx-post="{{ url_for('market.browse.product.cart', product_slug=p.slug) }}"
-            hx-target="#cart-mini"
-            hx-swap="outerHTML"
+            hx-post="{{ qty_url }}"
+            hx-swap="none"
           >
             <input type="hidden" name="csrf_token" value="{{ csrf_token() }}">
             <input

shared/infrastructure/factory.py

@@ -284,6 +284,6 @@ def create_base_app(
     # --- favicon ---
     @app.get("/favicon.ico")
     async def favicon():
-        return await send_from_directory("static", "favicon.ico")
+        return await send_from_directory(STATIC_DIR, "favicon.ico")
 
     return app