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/macros/links.html

@@ -5,11 +5,11 @@
     <div class="relative nav-group {{_class}}">
       <a
         href="{{ href }}"
-        hx-get="{{ href }}"
-        hx-target="#main-panel"
-        hx-select="{{select}}"
-        hx-swap="outerHTML"
-        hx-push-url="true"
+        sx-get="{{ href }}"
+        sx-target="#main-panel"
+        sx-select="{{select}}"
+        sx-swap="outerHTML"
+        sx-push-url="true"
         aria-selected="{{ 'true' if (request.path|host).startswith(href) else 'false' }}"
         {% if aclass %}
           class="{{aclass}}"
@@ -35,7 +35,7 @@
       id="{{id}}"
     {% endif %}
     {% if oob %}
-      hx-swap-oob="outerHTML"
+      sx-swap-oob="outerHTML"
     {% endif %}
     class="flex flex-col items-center md:flex-row justify-center md:justify-between w-full p-1 bg-{{menu_colour}}-{{(500-(level()*100))|string}}"
   >