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/bp/ticket_admin/routes.py

@@ -12,7 +12,7 @@ from __future__ import annotations
 import logging
 
 from quart import (
-    Blueprint, g, request, render_template, make_response, jsonify,
+    Blueprint, g, request, make_response,
 )
 from sqlalchemy import select, func
 from sqlalchemy.orm import selectinload
@@ -34,12 +34,10 @@ logger = logging.getLogger(__name__)
 def register() -> Blueprint:
     bp = Blueprint("ticket_admin", __name__, url_prefix="/admin/tickets")
 
-    @bp.get("/")
-    @require_admin
-    async def dashboard():
-        """Ticket admin dashboard with QR scanner and recent tickets."""
-        from shared.browser.app.utils.htmx import is_htmx_request
-
+    @bp.before_request
+    async def _prepare_page_data():
+        if "defpage_" not in (request.endpoint or ""):
+            return
         # Get recent tickets
         result = await g.s.execute(
             select(Ticket)
@@ -72,15 +70,9 @@ def register() -> Blueprint:
         }
 
         from shared.sx.page import get_template_context
-        from sx.sx_components import render_ticket_admin_page, render_ticket_admin_oob
-
+        from sx.sx_components import _ticket_admin_main_panel_html
         ctx = await get_template_context()
-        if not is_htmx_request():
-            html = await render_ticket_admin_page(ctx, tickets, stats)
-            return await make_response(html, 200)
-        else:
-            sx_src = await render_ticket_admin_oob(ctx, tickets, stats)
-            return sx_response(sx_src)
+        g.ticket_admin_content = _ticket_admin_main_panel_html(ctx, tickets, stats)
 
     @bp.get("/entry/<int:entry_id>/")
     @require_admin