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>

market/sexp/cart.sexpr

@@ -2,7 +2,7 @@
 
 (defcomp ~market-cart-add-empty (&key cart-id action csrf)
   (div :id cart-id
-    (form :action action :method "post" :hx-post action :hx-target "#cart-mini" :hx-swap "outerHTML" :class "rounded flex items-center"
+    (form :action action :method "post" :sx-post action :sx-target "#cart-mini" :sx-swap "outerHTML" :class "rounded flex items-center"
       (input :type "hidden" :name "csrf_token" :value csrf)
       (input :type "hidden" :name "count" :value "1")
       (button :type "submit" :class "relative inline-flex items-center justify-center text-sm font-medium text-stone-500 hover:bg-emerald-50"
@@ -12,7 +12,7 @@
 (defcomp ~market-cart-add-quantity (&key cart-id action csrf minus-val plus-val quantity cart-href)
   (div :id cart-id
     (div :class "rounded flex items-center gap-2"
-      (form :action action :method "post" :hx-post action :hx-target "#cart-mini" :hx-swap "outerHTML"
+      (form :action action :method "post" :sx-post action :sx-target "#cart-mini" :sx-swap "outerHTML"
         (input :type "hidden" :name "csrf_token" :value csrf)
         (input :type "hidden" :name "count" :value minus-val)
         (button :type "submit" :class "inline-flex items-center justify-center w-8 h-8 text-sm font-medium rounded-full border border-emerald-600 text-emerald-700 hover:bg-emerald-50 text-xl" "-"))
@@ -21,13 +21,13 @@
           (i :class "fa-solid fa-shopping-cart text-2xl" :aria-hidden "true")
           (span :class "absolute top-1/2 left-1/2 -translate-x-1/2 -translate-y-1/2 pointer-events-none"
             (span :class "flex items-center justify-center bg-black text-white rounded-full w-4 h-4 text-xs font-bold" quantity))))
-      (form :action action :method "post" :hx-post action :hx-target "#cart-mini" :hx-swap "outerHTML"
+      (form :action action :method "post" :sx-post action :sx-target "#cart-mini" :sx-swap "outerHTML"
         (input :type "hidden" :name "csrf_token" :value csrf)
         (input :type "hidden" :name "count" :value plus-val)
         (button :type "submit" :class "inline-flex items-center justify-center w-8 h-8 text-sm font-medium rounded-full border border-emerald-600 text-emerald-700 hover:bg-emerald-50 text-xl" "+")))))
 
 (defcomp ~market-cart-mini-count (&key href count)
-  (div :id "cart-mini" :hx-swap-oob "outerHTML"
+  (div :id "cart-mini" :sx-swap-oob "outerHTML"
     (a :href href :class "relative inline-flex items-center justify-center"
       (span :class "relative inline-flex items-center justify-center"
         (i :class "fa-solid fa-shopping-cart text-xl" :aria-hidden "true")
@@ -36,9 +36,10 @@
             count))))))
 
 (defcomp ~market-cart-mini-empty (&key href logo)
-  (div :id "cart-mini" :hx-swap-oob "outerHTML"
+  (div :id "cart-mini" :sx-swap-oob "outerHTML"
     (a :href href :class "relative inline-flex items-center justify-center"
       (img :src logo :class "h-8 w-8 rounded-full object-cover border border-stone-300" :alt ""))))
 
-(defcomp ~market-cart-add-oob (&key id inner-html)
-  (div :id id :hx-swap-oob "outerHTML" (raw! inner-html)))
+(defcomp ~market-cart-add-oob (&key id content inner)
+  (div :id id :sx-swap-oob "outerHTML"
+    (if content content (when inner inner))))