Phase 7: Replace render_template() with s-expression rendering in all POST/PUT/DELETE routes

Eliminates all render_template() calls from POST/PUT/DELETE handlers across
all 7 services. Moves sexp_components.py into sexp/ packages per service.

- Blog: like toggle, snippets, cache clear, features/sumup/entry panels,
  create/delete market, WYSIWYG editor panel (render_editor_panel)
- Federation: like/unlike/boost/unboost, follow/unfollow, actor card,
  interaction buttons
- Events: ticket widget, checkin, confirm/decline/provisional, tickets
  config, posts CRUD, description edit/save, calendar/slot/ticket_type
  CRUD, payments, buy tickets, day main panel, entry page
- Market: like toggle, cart add response
- Account: newsletter toggle
- Cart: checkout error pages (3 handlers)
- Orders: checkout error page (1 handler)

Remaining render_template() calls are exclusively in GET handlers and
internal services (email templates, fragment endpoints).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

events/bp/ticket_admin/routes.py

@@ -71,7 +71,7 @@ def register() -> Blueprint:
         }
 
         from shared.sexp.page import get_template_context
-        from sexp_components import render_ticket_admin_page, render_ticket_admin_oob
+        from sexp.sexp_components import render_ticket_admin_page, render_ticket_admin_oob
 
         ctx = await get_template_context()
         if not is_htmx_request():
@@ -100,11 +100,8 @@ def register() -> Blueprint:
 
         tickets = await get_tickets_for_entry(g.s, entry_id)
 
-        html = await render_template(
-            "_types/ticket_admin/_entry_tickets.html",
-            entry=entry,
-            tickets=tickets,
-        )
+        from sexp.sexp_components import render_entry_tickets_admin
+        html = render_entry_tickets_admin(entry, tickets)
         return await make_response(html, 200)
 
     @bp.get("/lookup/")
@@ -119,19 +116,12 @@ def register() -> Blueprint:
             )
 
         ticket = await get_ticket_by_code(g.s, code)
+        from sexp.sexp_components import render_lookup_result
         if not ticket:
-            html = await render_template(
-                "_types/ticket_admin/_lookup_result.html",
-                ticket=None,
-                error="Ticket not found",
-            )
+            html = render_lookup_result(None, "Ticket not found")
             return await make_response(html, 200)
 
-        html = await render_template(
-            "_types/ticket_admin/_lookup_result.html",
-            ticket=ticket,
-            error=None,
-        )
+        html = render_lookup_result(ticket, None)
         return await make_response(html, 200)
 
     @bp.post("/<code>/checkin/")
@@ -141,22 +131,13 @@ def register() -> Blueprint:
         """Check in a ticket by its code."""
         success, error = await checkin_ticket(g.s, code)
 
+        from sexp.sexp_components import render_checkin_result
         if not success:
-            html = await render_template(
-                "_types/ticket_admin/_checkin_result.html",
-                success=False,
-                error=error,
-                ticket=None,
-            )
+            html = render_checkin_result(False, error, None)
             return await make_response(html, 200)
 
         ticket = await get_ticket_by_code(g.s, code)
-        html = await render_template(
-            "_types/ticket_admin/_checkin_result.html",
-            success=True,
-            error=None,
-            ticket=ticket,
-        )
+        html = render_checkin_result(True, None, ticket)
         return await make_response(html, 200)
 
     return bp