Auto-mount defpages: eliminate Python route stubs across all 9 services

Defpages are now declared with absolute paths in .sx files and auto-mounted
directly on the Quart app, removing ~850 lines of blueprint mount_pages calls,
before_request hooks, and g.* wrapper boilerplate. A new page = one defpage
declaration, nothing else.

Infrastructure:
- async_eval awaits coroutine results from callable dispatch
- auto_mount_pages() mounts all registered defpages on the app
- g._defpage_ctx pattern passes helper data to layout context

Migrated: sx, account, orders, federation, cart, market, events, blog

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

events/app.py

@@ -171,19 +171,25 @@ def create_app() -> "Quart":
             "markets": markets,
         }
 
+    # Auto-mount all defpages with absolute paths
+    from shared.sx.pages import auto_mount_pages
+    auto_mount_pages(app, "events")
+
     # Tickets blueprint — user-facing ticket views and QR codes
     from bp.tickets.routes import register as 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
     ticket_admin_bp = register_ticket_admin()
-    mount_pages(ticket_admin_bp, "events", names=["ticket-admin"])
     app.register_blueprint(ticket_admin_bp)
 
+    # --- Pass defpage helper data to template context for layouts ---
+    @app.context_processor
+    async def inject_events_data():
+        return getattr(g, '_defpage_ctx', {})
+
     # --- oEmbed endpoint ---
     @app.get("/oembed")
     async def oembed():