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>

shared/browser/templates/social/_search_results.html

@@ -27,9 +27,9 @@
       <div class="flex-shrink-0">
         {% if a.actor_url in (followed_urls or []) %}
           <form method="post" action="{{ url_for('ap_social.unfollow') }}"
-                hx-post="{{ url_for('ap_social.unfollow') }}"
-                hx-target="closest article"
-                hx-swap="outerHTML">
+                sx-post="{{ url_for('ap_social.unfollow') }}"
+                sx-target="closest article"
+                sx-swap="outerHTML">
             <input type="hidden" name="csrf_token" value="{{ csrf_token() }}">
             <input type="hidden" name="actor_url" value="{{ a.actor_url }}">
             <button type="submit" class="text-sm border border-stone-300 rounded px-3 py-1 hover:bg-stone-100">
@@ -38,9 +38,9 @@
           </form>
         {% else %}
           <form method="post" action="{{ url_for('ap_social.follow') }}"
-                hx-post="{{ url_for('ap_social.follow') }}"
-                hx-target="closest article"
-                hx-swap="outerHTML">
+                sx-post="{{ url_for('ap_social.follow') }}"
+                sx-target="closest article"
+                sx-swap="outerHTML">
             <input type="hidden" name="csrf_token" value="{{ csrf_token() }}">
             <input type="hidden" name="actor_url" value="{{ a.actor_url }}">
             <button type="submit" class="text-sm bg-stone-800 text-white rounded px-3 py-1 hover:bg-stone-700">
@@ -54,8 +54,8 @@
 {% endfor %}
 
 {% if actors | length >= 20 %}
-  <div hx-get="{{ url_for('ap_social.search_page', q=query, page=page + 1) }}"
-       hx-trigger="revealed"
-       hx-swap="outerHTML">
+  <div sx-get="{{ url_for('ap_social.search_page', q=query, page=page + 1) }}"
+       sx-trigger="revealed"
+       sx-swap="outerHTML">
   </div>
 {% endif %}