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/sexp/templates/cards.sexp

@@ -1,14 +1,14 @@
 (defcomp ~post-card (&key title slug href feature-image excerpt
                           status published-at updated-at publish-requested
-                          hx-select like-html widgets-html at-bar-html)
+                          hx-select like widgets at-bar)
   (article :class "border-b pb-6 last:border-b-0 relative"
-    (when like-html (raw! like-html))
+    (when like like)
     (a :href href
-       :hx-get href
-       :hx-target "#main-panel"
-       :hx-select hx-select
-       :hx-swap "outerHTML"
-       :hx-push-url "true"
+       :sx-get href
+       :sx-target "#main-panel"
+       :sx-select hx-select
+       :sx-swap "outerHTML"
+       :sx-push-url "true"
        :class "block rounded-xl bg-white shadow hover:shadow-md transition overflow-hidden"
       (header :class "mb-2 text-center"
         (h2 :class "text-4xl font-bold text-stone-900" title)
@@ -28,8 +28,8 @@
           (img :src feature-image :alt "" :class "rounded-lg w-full object-cover")))
       (when excerpt
         (p :class "text-stone-700 text-lg leading-relaxed text-center" excerpt)))
-    (when widgets-html (raw! widgets-html))
-    (when at-bar-html (raw! at-bar-html))))
+    (when widgets widgets)
+    (when at-bar at-bar)))
 
 (defcomp ~order-summary-card (&key order-id created-at description status currency total-amount)
   (div :class "rounded-2xl border border-stone-200 bg-white/80 p-4 sm:p-6 space-y-2 text-xs sm:text-sm text-stone-800"