Phase 4: add container-nav/cards fragment handlers, use market fragment

Events provides container-nav (calendar entries + links) and
container-cards (batch entries for blog listing) as fragments.
Day and entry routes fetch market container-nav via fragment instead
of widget registry.

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

bp/calendar_entry/routes.py

@@ -27,7 +27,7 @@ from datetime import datetime, timezone
 import math
 import logging
 
-from shared.services.widget_registry import widgets
+from shared.infrastructure.fragments import fetch_fragment
 
 from ..ticket_types.routes import register as register_ticket_types
 
@@ -222,25 +222,17 @@ def register():
                             ticket_type_id=tt.id,
                         )
 
-        # Widget-driven container nav (market links, etc.)
-        container_nav_loaded = []
+        # Fetch container nav from market (skip calendar — we're on a calendar page)
+        container_nav_html = ""
         post_data = getattr(g, "post_data", None)
         if post_data:
             post_id = post_data["post"]["id"]
             post_slug = post_data["post"]["slug"]
-            for w in widgets.container_nav:
-                if w.domain.startswith("calendar"):
-                    continue  # skip — we're already on a calendar page
-                try:
-                    wctx = await w.context_fn(
-                        g.s, container_type="page", container_id=post_id,
-                        post_slug=post_slug,
-                    )
-                    has_data = any(v for v in wctx.values() if isinstance(v, list) and v)
-                    if has_data:
-                        container_nav_loaded.append({"widget": w, "ctx": wctx})
-                except Exception:
-                    pass
+            container_nav_html = await fetch_fragment("market", "container-nav", params={
+                "container_type": "page",
+                "container_id": str(post_id),
+                "post_slug": post_slug,
+            })
 
         return {
             "entry": calendar_entry,
@@ -249,7 +241,7 @@ def register():
             "ticket_sold_count": ticket_sold_count,
             "user_ticket_count": user_ticket_count,
             "user_ticket_counts_by_type": user_ticket_counts_by_type,
-            "container_nav_widgets": container_nav_loaded,
+            "container_nav_html": container_nav_html,
         }
     @bp.get("/")
     @require_admin