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/markets/routes.py

@@ -24,7 +24,7 @@ def register():
     @bp.get("/")
     async def home(**kwargs):
         from shared.sexp.page import get_template_context
-        from sexp_components import render_markets_page, render_markets_oob
+        from sexp.sexp_components import render_markets_page, render_markets_oob
 
         ctx = await get_template_context()
         if not is_htmx_request():
@@ -52,7 +52,10 @@ def register():
         except Exception as e:
             return await make_response(f'<div class="text-red-600 text-sm">{e}</div>', 422)
 
-        html = await render_template("_types/markets/index.html")
+        from shared.sexp.page import get_template_context
+        from sexp.sexp_components import render_markets_list_panel
+        ctx = await get_template_context()
+        html = render_markets_list_panel(ctx)
         return await make_response(html)
 
     @bp.delete("/<market_slug>/")
@@ -63,7 +66,10 @@ def register():
         if not deleted:
             return await make_response("Market not found", 404)
 
-        html = await render_template("_types/markets/index.html")
+        from shared.sexp.page import get_template_context
+        from sexp.sexp_components import render_markets_list_panel
+        ctx = await get_template_context()
+        html = render_markets_list_panel(ctx)
         return await make_response(html)
 
     return bp