Add village hall page summary with infinite scroll

New /<slug>/ route shows upcoming confirmed events across all calendars
for a container. Features list/tile view toggle, date-grouped cards,
ticket +/- cart widgets, and infinite scroll pagination.

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

bp/__init__.py

@@ -1,3 +1,4 @@
 from .calendars.routes import register as register_calendars
 from .markets.routes import register as register_markets
 from .payments.routes import register as register_payments
+from .page.routes import register as register_page