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/layout.html

@@ -13,7 +13,7 @@
         <div
           id="{{id}}"
           {% if oob %}
-          hx-swap-oob="true"
+          sx-swap-oob="true"
           {% endif %}
           class="{{'flex justify-between items-start gap-2' if not _class else _class}}">
           {{ caller() }}
@@ -55,7 +55,7 @@
 
 
 {% macro menu(id, _class="") %}
-  <div id="{{id}}" hx-swap-oob="outerHTML" class="{{_class}}">
+  <div id="{{id}}" sx-swap-oob="outerHTML" class="{{_class}}">
     {{ caller() }}
   </div>
 {%- endmacro %}