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>

federation/sexp/notifications.sexpr

@@ -1,25 +1,25 @@
 ;; Notification components
 
 (defcomp ~federation-notification-preview (&key preview)
-  (div :class "text-sm text-stone-500 mt-1 truncate" (raw! preview)))
+  (div :class "text-sm text-stone-500 mt-1 truncate" preview))
 
-(defcomp ~federation-notification-card (&key cls avatar-html from-name from-username from-domain action-text preview-html time-html)
+(defcomp ~federation-notification-card (&key cls avatar from-name from-username from-domain action-text preview time)
   (div :class cls
     (div :class "flex items-start gap-3"
-      (raw! avatar-html)
+      avatar
       (div :class "flex-1"
         (div :class "text-sm"
-          (span :class "font-semibold" (raw! from-name))
-          " " (span :class "text-stone-500" "@" (raw! from-username) (raw! from-domain))
-          " " (span :class "text-stone-600" (raw! action-text)))
-        (raw! preview-html)
-        (div :class "text-xs text-stone-400 mt-1" (raw! time-html))))))
+          (span :class "font-semibold" from-name)
+          " " (span :class "text-stone-500" "@" from-username from-domain)
+          " " (span :class "text-stone-600" action-text))
+        preview
+        (div :class "text-xs text-stone-400 mt-1" time)))))
 
 (defcomp ~federation-notifications-empty ()
   (p :class "text-stone-500" "No notifications yet."))
 
-(defcomp ~federation-notifications-list (&key items-html)
-  (div :class "space-y-2" (raw! items-html)))
+(defcomp ~federation-notifications-list (&key items)
+  (div :class "space-y-2" items))
 
-(defcomp ~federation-notifications-page (&key notifs-html)
-  (h1 :class "text-2xl font-bold mb-6" "Notifications") (raw! notifs-html))
+(defcomp ~federation-notifications-page (&key notifs)
+  (h1 :class "text-2xl font-bold mb-6" "Notifications") notifs)