Add cart-mini and account-nav-item fragment handlers

Phase 2 of fragment composition: cart exposes cart-mini fragment
(icon + item count badge) and account-nav-item fragment (orders
link) via /internal/fragments/ endpoint. Updates shared submodule.

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

bp/fragments/routes.py

@@ -2,11 +2,15 @@
 
 Exposes HTML fragments at ``/internal/fragments/<type>`` for consumption
 by other coop apps via the fragment client.
+
+Fragments:
+  cart-mini          Cart icon with badge (or logo when empty)
+  account-nav-item   "orders" link for account dashboard
 """
 
 from __future__ import annotations
 
-from quart import Blueprint, Response, request
+from quart import Blueprint, Response, request, render_template, g
 
 from shared.infrastructure.fragments import FRAGMENT_HEADER
 
@@ -14,7 +18,41 @@ from shared.infrastructure.fragments import FRAGMENT_HEADER
 def register():
     bp = Blueprint("fragments", __name__, url_prefix="/internal/fragments")
 
-    _handlers: dict[str, object] = {}
+    # ---------------------------------------------------------------
+    # Fragment handlers
+    # ---------------------------------------------------------------
+
+    async def _cart_mini():
+        from shared.services.registry import services
+
+        user_id = request.args.get("user_id", type=int)
+        session_id = request.args.get("session_id")
+
+        summary = await services.cart.cart_summary(
+            g.s, user_id=user_id, session_id=session_id,
+        )
+        count = summary.count + summary.calendar_count + summary.ticket_count
+        return await render_template("fragments/cart_mini.html", cart_count=count)
+
+    async def _account_nav_item():
+        from shared.infrastructure.urls import cart_url
+
+        href = cart_url("/orders/")
+        return (
+            '<div class="relative nav-group">'
+            f'<a href="{href}" class="justify-center cursor-pointer flex flex-row '
+            'items-center gap-2 rounded bg-stone-200 text-black p-3" data-hx-disable>'
+            'orders</a></div>'
+        )
+
+    _handlers = {
+        "cart-mini": _cart_mini,
+        "account-nav-item": _account_nav_item,
+    }
+
+    # ---------------------------------------------------------------
+    # Routing
+    # ---------------------------------------------------------------
 
     @bp.before_request
     async def _require_fragment_header():
@@ -29,6 +67,4 @@ def register():
         html = await handler()
         return Response(html, status=200, content_type="text/html")
 
-    bp._fragment_handlers = _handlers
-
     return bp