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>

cart/bp/cart/overview_routes.py

@@ -14,18 +14,16 @@ def register(url_prefix: str) -> Blueprint:
     @bp.get("/")
     async def overview():
         from quart import g
+        from shared.sexp.page import get_template_context
+        from sexp_components import render_overview_page, render_overview_oob
+
         page_groups = await get_cart_grouped_by_page(g.s)
+        ctx = await get_template_context()
 
         if not is_htmx_request():
-            html = await render_template(
-                "_types/cart/overview/index.html",
-                page_groups=page_groups,
-            )
+            html = await render_overview_page(ctx, page_groups)
         else:
-            html = await render_template(
-                "_types/cart/overview/_oob_elements.html",
-                page_groups=page_groups,
-            )
+            html = await render_overview_oob(ctx, page_groups)
         return await make_response(html)
 
     return bp

cart/bp/cart/page_routes.py

@@ -40,10 +40,20 @@ def register(url_prefix: str) -> Blueprint:
             ticket_total=ticket_total,
         )
 
+        from shared.sexp.page import get_template_context
+        from sexp_components import render_page_cart_page, render_page_cart_oob
+
+        ctx = await get_template_context()
         if not is_htmx_request():
-            html = await render_template("_types/cart/page/index.html", **tpl_ctx)
+            html = await render_page_cart_page(
+                ctx, post, cart, cal_entries, page_tickets,
+                ticket_groups, total, calendar_total, ticket_total,
+            )
         else:
-            html = await render_template("_types/cart/page/_oob_elements.html", **tpl_ctx)
+            html = await render_page_cart_oob(
+                ctx, post, cart, cal_entries, page_tickets,
+                ticket_groups, total, calendar_total, ticket_total,
+            )
         return await make_response(html)
 
     @bp.post("/checkout/")