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/slots/routes.py

@@ -20,6 +20,7 @@ from shared.browser.app.utils import (
     parse_cost
 )
 from shared.browser.app.utils.htmx import is_htmx_request
+from shared.sexp.helpers import sexp_response
 
 
 def register():
@@ -50,9 +51,10 @@ def register():
         tctx = await get_template_context()
         if not is_htmx_request():
             html = await render_slots_page(tctx)
+            return await make_response(html)
         else:
-            html = await render_slots_oob(tctx)
-        return await make_response(html)
+            sexp_src = await render_slots_oob(tctx)
+            return sexp_response(sexp_src)
 
 
     @bp.post("/")
@@ -128,8 +130,7 @@ def register():
         # Success → re-render the slots table
         slots = await svc_list_slots(g.s, g.calendar.id)
         from sexp.sexp_components import render_slots_table
-        html = render_slots_table(slots, g.calendar)
-        return await make_response(html)
+        return sexp_response(render_slots_table(slots, g.calendar))
 
         
     @bp.get("/add")