Externalize sexp to .sexpr files + render() API

Replace all 676 inline sexp() string calls across 7 services with
render(component_name, **kwargs) calls backed by 46 external .sexpr
component definition files (587 defcomps total).

- Add render() function to shared/sexp/jinja_bridge.py
- Add load_service_components() helper and update load_sexp_dir() for *.sexpr
- Update parser keyword regex to support HTMX hx-on::event syntax
- Convert remaining inline HTML in route files to render() calls
- Add shared/sexp/templates/misc.sexp for cross-service utility components

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

federation/bp/social/routes.py

@@ -422,8 +422,9 @@ def register(url_prefix="/social"):
             return Response("0", content_type="text/plain")
         count = await services.federation.unread_notification_count(g.s, actor.id)
         if count > 0:
+            from shared.sexp.jinja_bridge import render as render_comp
             return Response(
-                f'<span class="bg-red-500 text-white text-xs rounded-full px-1.5 py-0.5">{count}</span>',
+                render_comp("notification-badge", count=str(count)),
                 content_type="text/html",
             )
         return Response("", content_type="text/html")