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/calendar/admin/routes.py

@@ -20,7 +20,7 @@ def register():
         from shared.browser.app.utils.htmx import is_htmx_request
 
         from shared.sexp.page import get_template_context
-        from sexp_components import render_calendar_admin_page, render_calendar_admin_oob
+        from sexp.sexp_components import render_calendar_admin_page, render_calendar_admin_oob
 
         tctx = await get_template_context()
         if not is_htmx_request():
@@ -34,12 +34,8 @@ def register():
     @bp.get("/description/")
     @require_admin
     async def calendar_description_edit(calendar_slug: str, **kwargs):
-        # g.post and g.calendar should already be set by the parent calendar bp
-        html = await render_template(
-            "_types/calendar/admin/_description_edit.html",
-            post=g.post_data['post'],
-            calendar=g.calendar,
-        )
+        from sexp.sexp_components import render_calendar_description_edit
+        html = render_calendar_description_edit(g.calendar)
         return await make_response(html)
 
 
@@ -54,24 +50,16 @@ def register():
         g.calendar.description = description
         await g.s.flush()
 
-        html = await render_template(
-            "_types/calendar/admin/_description.html",
-            post=g.post_data['post'],
-            calendar=g.calendar,
-            oob=True
-        )
+        from sexp.sexp_components import render_calendar_description
+        html = render_calendar_description(g.calendar, oob=True)
         return await make_response(html)
 
 
     @bp.get("/description/view/")
     @require_admin
     async def calendar_description_view(calendar_slug: str, **kwargs):
-        # just render the display version without touching the DB (used by Cancel)
-        html = await render_template(
-            "_types/calendar/admin/_description.html",
-            post=g.post_data['post'],
-            calendar=g.calendar,
-        )
+        from sexp.sexp_components import render_calendar_description
+        html = render_calendar_description(g.calendar)
         return await make_response(html)
     
     return bp