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>

events/bp/calendars/routes.py

@@ -66,7 +66,8 @@ def register():
         try:
             await svc_create_calendar(g.s, post_id, name)
         except Exception as e:
-            return await make_response(f'<div class="text-red-600 text-sm">{e}</div>', 422)
+            from shared.sexp.jinja_bridge import render as render_comp
+            return await make_response(render_comp("error-inline", message=str(e)), 422)
 
         from shared.sexp.page import get_template_context
         from sexp.sexp_components import render_calendars_list_panel