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>

events/bp/tickets/routes.py

@@ -20,6 +20,7 @@ from sqlalchemy.orm import selectinload
 from models.calendars import CalendarEntry
 from shared.infrastructure.cart_identity import current_cart_identity
 from shared.browser.app.redis_cacher import clear_cache
+from shared.sexp.helpers import sexp_response
 
 from .services.tickets import (
     create_ticket,
@@ -56,10 +57,10 @@ def register() -> Blueprint:
         ctx = await get_template_context()
         if not is_htmx_request():
             html = await render_tickets_page(ctx, tickets)
+            return await make_response(html, 200)
         else:
-            html = await render_tickets_oob(ctx, tickets)
-
-        return await make_response(html, 200)
+            sexp_src = await render_tickets_oob(ctx, tickets)
+            return sexp_response(sexp_src)
 
     @bp.get("/<code>/")
     async def ticket_detail(code: str):
@@ -87,10 +88,10 @@ def register() -> Blueprint:
         ctx = await get_template_context()
         if not is_htmx_request():
             html = await render_ticket_detail_page(ctx, ticket)
+            return await make_response(html, 200)
         else:
-            html = await render_ticket_detail_oob(ctx, ticket)
-
-        return await make_response(html, 200)
+            sexp_src = await render_ticket_detail_oob(ctx, ticket)
+            return sexp_response(sexp_src)
 
     @bp.post("/buy/")
     @clear_cache(tag="calendars", tag_scope="all")
@@ -182,8 +183,7 @@ def register() -> Blueprint:
         cart_count = summary.count + summary.calendar_count + summary.ticket_count
 
         from sexp.sexp_components import render_buy_result
-        html = render_buy_result(entry, created, remaining, cart_count)
-        return await make_response(html, 200)
+        return sexp_response(render_buy_result(entry, created, remaining, cart_count))
 
     @bp.post("/adjust/")
     @clear_cache(tag="calendars", tag_scope="all")
@@ -306,11 +306,9 @@ def register() -> Blueprint:
         cart_count = summary.count + summary.calendar_count + summary.ticket_count
 
         from sexp.sexp_components import render_adjust_response
-        html = render_adjust_response(
+        return sexp_response(render_adjust_response(
             entry, ticket_remaining, ticket_sold_count,
             user_ticket_count, user_ticket_counts_by_type, cart_count,
-        )
-
-        return await make_response(html, 200)
+        ))
 
     return bp