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/slot/routes.py

@@ -1,7 +1,7 @@
 from __future__ import annotations
 
 from quart import (
-    request, render_template, make_response, Blueprint, g, jsonify
+    request, make_response, Blueprint, g, jsonify
 )
 from sqlalchemy.exc import IntegrityError
 
@@ -23,33 +23,32 @@ from shared.browser.app.utils import (
     parse_time,
     parse_cost
 )
-from shared.browser.app.utils.htmx import is_htmx_request
 from shared.sx.helpers import sx_response
 
 
 def register():
     bp = Blueprint("slot", __name__, url_prefix='/<int:slot_id>')
-    
-    # ---------- Pages ----------
 
-    @bp.get("/")
-    @require_admin
-    async def get(slot_id: int, **kwargs):
-        slot = await svc_get_slot(g.s, slot_id)
+    @bp.before_request
+    async def _prepare_page_data():
+        if "defpage_" not in (request.endpoint or ""):
+            return
+        slot_id = (request.view_args or {}).get("slot_id")
+        slot = await svc_get_slot(g.s, slot_id) if slot_id else None
         if not slot:
-            return await make_response("Not found", 404)
-        
-        from shared.sx.page import get_template_context
-        from sx.sx_components import render_slot_page, render_slot_oob
+            from quart import abort
+            abort(404)
+        g.slot = slot
+        calendar = getattr(g, "calendar", None)
+        from sx.sx_components import render_slot_main_panel
+        g.slot_content = render_slot_main_panel(slot, calendar)
 
-        tctx = await get_template_context()
-        if not is_htmx_request():
-            html = await render_slot_page(tctx)
-            return await make_response(html)
-        else:
-            sx_src = await render_slot_oob(tctx)
-            return sx_response(sx_src)
+    @bp.context_processor
+    async def _inject_slot():
+        return {"slot": getattr(g, "slot", None)}
 
+    from shared.sx.pages import mount_pages
+    mount_pages(bp, "events", names=["slot-detail"])
 
     @bp.get("/edit/")
     @require_admin