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>

orders/app.py

@@ -1,5 +1,6 @@
 from __future__ import annotations
 import path_setup  # noqa: F401  # adds shared/ to sys.path
+import sexp_components  # noqa: F401  # ensure Hypercorn --reload watches this file
 
 from pathlib import Path
 from types import SimpleNamespace
@@ -69,6 +70,10 @@ def create_app() -> "Quart":
         app.jinja_loader,
     ])
 
+    # Load orders-specific s-expression components
+    from sexp_components import load_orders_components
+    load_orders_components()
+
     app.register_blueprint(register_fragments())
     app.register_blueprint(register_actions())
     app.register_blueprint(register_data())