Send all responses as sexp wire format with client-side rendering

- Server sends sexp source text, client (sexp.js) renders everything
- SexpExpr marker class for nested sexp composition in serialize()
- sexp_page() HTML shell with data-mount="body" for full page loads
- sexp_response() returns text/sexp for OOB/partial responses
- ~app-body layout component replaces ~app-layout (no raw!)
- ~rich-text is the only component using raw! (for CMS HTML content)
- Fragment endpoints return text/sexp, auto-wrapped in SexpExpr
- All _*_html() helpers converted to _*_sexp() returning sexp source
- Head auto-hoist: sexp.js moves meta/title/link/script[ld+json]
  from rendered body to document.head automatically
- Unknown components render warning box instead of crashing page
- Component kwargs preserve AST for lazy rendering (fixes <> in kwargs)
- Fix unterminated paren in events/sexp/tickets.sexpr

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

federation/bp/fragments/routes.py

@@ -1,6 +1,6 @@
 """Federation app fragment endpoints.
 
-Exposes HTML fragments at ``/internal/fragments/<type>`` for consumption
+Exposes sexp fragments at ``/internal/fragments/<type>`` for consumption
 by other coop apps via the fragment client.
 """
 
@@ -9,7 +9,6 @@ from __future__ import annotations
 from quart import Blueprint, Response, request
 
 from shared.infrastructure.fragments import FRAGMENT_HEADER
-from shared.sexp.jinja_bridge import sexp
 
 
 def register():
@@ -26,23 +25,22 @@ def register():
     async def get_fragment(fragment_type: str):
         handler = _handlers.get(fragment_type)
         if handler is None:
-            return Response("", status=200, content_type="text/html")
-        html = await handler()
-        return Response(html, status=200, content_type="text/html")
+            return Response("", status=200, content_type="text/sexp")
+        src = await handler()
+        return Response(src, status=200, content_type="text/sexp")
 
     # --- link-card fragment: actor profile preview card --------------------------
 
-    def _render_federation_link_card(actor, link: str) -> str:
-        return sexp(
-            '(~link-card :link link :title title :image image'
-            ' :icon "fas fa-user" :subtitle username'
-            ' :detail summary :data-app "federation")',
-            link=link,
-            title=actor.display_name or actor.preferred_username,
-            image=None,
-            username=f"@{actor.preferred_username}" if actor.preferred_username else None,
-            summary=actor.summary,
-        )
+    def _federation_link_card_sexp(actor, link: str) -> str:
+        from shared.sexp.helpers import sexp_call
+        return sexp_call("link-card",
+                         link=link,
+                         title=actor.display_name or actor.preferred_username,
+                         image=None,
+                         icon="fas fa-user",
+                         subtitle=f"@{actor.preferred_username}" if actor.preferred_username else None,
+                         detail=actor.summary,
+                         data_app="federation")
 
     async def _link_card_handler():
         from quart import g
@@ -61,7 +59,7 @@ def register():
                 parts.append(f"<!-- fragment:{u} -->")
                 actor = await services.federation.get_actor_by_username(g.s, u)
                 if actor:
-                    parts.append(_render_federation_link_card(
+                    parts.append(_federation_link_card_sexp(
                         actor, federation_url(f"/users/{actor.preferred_username}"),
                     ))
             return "\n".join(parts)
@@ -73,7 +71,7 @@ def register():
         actor = await services.federation.get_actor_by_username(g.s, lookup)
         if not actor:
             return ""
-        return _render_federation_link_card(
+        return _federation_link_card_sexp(
             actor, federation_url(f"/users/{actor.preferred_username}"),
         )