Migrate all apps to defpage declarative page routes

Replace Python GET page handlers with declarative defpage definitions in .sx
files across all 8 apps (sx docs, orders, account, market, cart, federation,
events, blog). Each app now has sxc/pages/ with setup functions, layout
registrations, page helpers, and .sx defpage declarations.

Core infrastructure: add g I/O primitive, PageDef support for auth/layout/
data/content/filter/aside/menu slots, post_author auth level, and custom
layout registration. Remove ~1400 lines of render_*_page/render_*_oob
boilerplate. Update all endpoint references in routes, sx_components, and
templates to defpage_* naming.

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

events/app.py

@@ -78,6 +78,10 @@ def create_app() -> "Quart":
         app.jinja_loader,
     ])
 
+    # --- defpage setup ---
+    from sxc.pages import setup_events_pages
+    setup_events_pages()
+
     # All events: / — global view across all pages
     app.register_blueprint(
         register_all_events(),
@@ -169,11 +173,16 @@ def create_app() -> "Quart":
 
     # Tickets blueprint — user-facing ticket views and QR codes
     from bp.tickets.routes import register as register_tickets
-    app.register_blueprint(register_tickets())
+    tickets_bp = register_tickets()
+    from shared.sx.pages import mount_pages
+    mount_pages(tickets_bp, "events", names=["my-tickets", "ticket-detail"])
+    app.register_blueprint(tickets_bp)
 
     # Ticket admin — check-in interface (admin only)
     from bp.ticket_admin.routes import register as register_ticket_admin
-    app.register_blueprint(register_ticket_admin())
+    ticket_admin_bp = register_ticket_admin()
+    mount_pages(ticket_admin_bp, "events", names=["ticket-admin"])
+    app.register_blueprint(ticket_admin_bp)
 
     # --- oEmbed endpoint ---
     @app.get("/oembed")