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/fragments.sexp

@@ -3,7 +3,7 @@
      :class "block rounded border border-stone-200 bg-white hover:bg-stone-50 transition-colors no-underline"
      :data-fragment "link-card"
      :data-app data-app
-     :data-hx-disable true
+     :sx-disable true
     (div :class "flex flex-row items-start gap-3 p-3"
       (if image
         (img :src image :alt "" :class "flex-shrink-0 w-16 h-16 rounded object-cover")
@@ -18,7 +18,7 @@
 
 (defcomp ~cart-mini (&key cart-count blog-url cart-url oob)
   (div :id "cart-mini"
-       :hx-swap-oob oob
+       :sx-swap-oob oob
     (if (= cart-count 0)
       (div :class "h-12 w-12 rounded-full overflow-hidden border border-stone-300 flex-shrink-0"
         (a :href blog-url
@@ -58,5 +58,5 @@
   (div :class "relative nav-group"
     (a :href href
        :class "justify-center cursor-pointer flex flex-row items-center gap-2 rounded bg-stone-200 text-black p-3"
-       :data-hx-disable true
+       :sx-disable true
       label)))