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>

orders/bp/order/routes.py

@@ -55,9 +55,11 @@ def register() -> Blueprint:
 
         if not is_htmx_request():
             html = await render_order_page(ctx, order, calendar_entries, url_for)
+            return await make_response(html)
         else:
-            html = await render_order_oob(ctx, order, calendar_entries, url_for)
-        return await make_response(html)
+            from shared.sexp.helpers import sexp_response
+            sexp_src = await render_order_oob(ctx, order, calendar_entries, url_for)
+            return sexp_response(sexp_src)
 
     @bp.get("/pay/")
     async def order_pay(order_id: int):