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>

shared/browser/app/errors.py

@@ -138,16 +138,12 @@ def errors(app):
         messages = getattr(e, "messages", [str(e)])
 
         if request.headers.get("HX-Request") == "true":
-            # Build a little styled <ul><li>...</li></ul> snippet
-            lis = "".join(
-                f"<li>{escape(m)}</li>"
+            from shared.sexp.jinja_bridge import render as render_comp
+            items = "".join(
+                render_comp("error-list-item", message=str(escape(m)))
                 for m in messages if m
             )
-            html = (
-                "<ul class='list-disc pl-5 space-y-1 text-sm text-red-600'>"
-                f"{lis}"
-                "</ul>"
-            )
+            html = render_comp("error-list", items_html=items)
             return await make_response(html, status)
 
         # Non-HTMX: show a nicer page with error messages
@@ -164,8 +160,9 @@ def errors(app):
         # Extract service name from "Fragment account/auth-menu failed: ..."
         service = msg.split("/")[0].replace("Fragment ", "") if "/" in msg else "unknown"
         if request.headers.get("HX-Request") == "true":
+            from shared.sexp.jinja_bridge import render as render_comp
             return await make_response(
-                f"<p class='text-sm text-red-600'>Service <b>{escape(service)}</b> is unavailable.</p>",
+                render_comp("fragment-error", service=str(escape(service))),
                 503,
             )
         # Raw HTML — cannot use render_template here because the context