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/prices.sexpr

@@ -9,8 +9,8 @@
 (defcomp ~market-price-regular (&key price)
   (div :class "mt-1 text-lg font-semibold" price))
 
-(defcomp ~market-price-line (&key inner-html)
-  (div :class "mt-1 flex items-baseline gap-2 justify-center" (raw! inner-html)))
+(defcomp ~market-price-line (&key inner)
+  (div :class "mt-1 flex items-baseline gap-2 justify-center" inner))
 
 (defcomp ~market-header-price-special-label ()
   (div :class "text-md font-bold text-emerald-700" "Special price"))
@@ -30,5 +30,5 @@
 (defcomp ~market-header-rrp (&key rrp)
   (div :class "text-base text-stone-400" (span "rrp:") " " (span rrp)))
 
-(defcomp ~market-prices-row (&key inner-html)
-  (div :class "flex flex-row items-center justify-between md:gap-2 md:px-2" (raw! inner-html)))
+(defcomp ~market-prices-row (&key inner)
+  (div :class "flex flex-row items-center justify-between md:gap-2 md:px-2" inner))