Phase 6: Replace render_template() with s-expression rendering in all GET routes

Migrate ~52 GET route handlers across all 7 services from Jinja
render_template() to s-expression component rendering. Each service
gets a sexp_components.py with page/oob/cards render functions.

- Add per-service sexp_components.py (account, blog, cart, events,
  federation, market, orders) with full page, OOB, and pagination
  card rendering
- Add shared/sexp/helpers.py with call_url, root_header_html,
  full_page, oob_page utilities
- Update all GET routes to use get_template_context() + render fns
- Fix get_template_context() to inject Jinja globals (URL helpers)
- Add qs_filter to base_context for sexp filter URL building
- Mount sexp_components.py in docker-compose.dev.yml for all services
- Import sexp_components in app.py for Hypercorn --reload watching
- Fix route_prefix import (shared.utils not shared.infrastructure.urls)
- Fix federation choose-username missing actor in context
- Fix market page_markets missing post in context

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

events/bp/calendar/admin/routes.py

@@ -19,13 +19,14 @@ def register():
     async def admin(calendar_slug: str, **kwargs):
         from shared.browser.app.utils.htmx import is_htmx_request
 
-        # Determine which template to use based on request type
+        from shared.sexp.page import get_template_context
+        from sexp_components import render_calendar_admin_page, render_calendar_admin_oob
+
+        tctx = await get_template_context()
         if not is_htmx_request():
-            # Normal browser request: full page with layout
-            html = await render_template("_types/calendar/admin/index.html")
+            html = await render_calendar_admin_page(tctx)
         else:
-            # HTMX request: main panel + OOB elements
-            html = await render_template("_types/calendar/admin/_oob_elements.html")
+            html = await render_calendar_admin_oob(tctx)
 
         return await make_response(html)