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>

docker-compose.dev.yml

@@ -45,7 +45,7 @@ services:
       - ./blog/alembic.ini:/app/blog/alembic.ini:ro
       - ./blog/alembic:/app/blog/alembic:ro
       - ./blog/app.py:/app/app.py
-      - ./blog/sexp_components.py:/app/sexp_components.py
+      - ./blog/sexp:/app/sexp
       - ./blog/bp:/app/bp
       - ./blog/services:/app/services
       - ./blog/templates:/app/templates
@@ -83,7 +83,7 @@ services:
       - ./market/alembic.ini:/app/market/alembic.ini:ro
       - ./market/alembic:/app/market/alembic:ro
       - ./market/app.py:/app/app.py
-      - ./market/sexp_components.py:/app/sexp_components.py
+      - ./market/sexp:/app/sexp
       - ./market/bp:/app/bp
       - ./market/services:/app/services
       - ./market/templates:/app/templates
@@ -120,7 +120,7 @@ services:
       - ./cart/alembic.ini:/app/cart/alembic.ini:ro
       - ./cart/alembic:/app/cart/alembic:ro
       - ./cart/app.py:/app/app.py
-      - ./cart/sexp_components.py:/app/sexp_components.py
+      - ./cart/sexp:/app/sexp
       - ./cart/bp:/app/bp
       - ./cart/services:/app/services
       - ./cart/templates:/app/templates
@@ -157,7 +157,7 @@ services:
       - ./events/alembic.ini:/app/events/alembic.ini:ro
       - ./events/alembic:/app/events/alembic:ro
       - ./events/app.py:/app/app.py
-      - ./events/sexp_components.py:/app/sexp_components.py
+      - ./events/sexp:/app/sexp
       - ./events/bp:/app/bp
       - ./events/services:/app/services
       - ./events/templates:/app/templates
@@ -194,7 +194,7 @@ services:
       - ./federation/alembic.ini:/app/federation/alembic.ini:ro
       - ./federation/alembic:/app/federation/alembic:ro
       - ./federation/app.py:/app/app.py
-      - ./federation/sexp_components.py:/app/sexp_components.py
+      - ./federation/sexp:/app/sexp
       - ./federation/bp:/app/bp
       - ./federation/services:/app/services
       - ./federation/templates:/app/templates
@@ -231,7 +231,7 @@ services:
       - ./account/alembic.ini:/app/account/alembic.ini:ro
       - ./account/alembic:/app/account/alembic:ro
       - ./account/app.py:/app/app.py
-      - ./account/sexp_components.py:/app/sexp_components.py
+      - ./account/sexp:/app/sexp
       - ./account/bp:/app/bp
       - ./account/services:/app/services
       - ./account/templates:/app/templates
@@ -330,7 +330,7 @@ services:
       - ./orders/alembic.ini:/app/orders/alembic.ini:ro
       - ./orders/alembic:/app/orders/alembic:ro
       - ./orders/app.py:/app/app.py
-      - ./orders/sexp_components.py:/app/sexp_components.py
+      - ./orders/sexp:/app/sexp
       - ./orders/bp:/app/bp
       - ./orders/services:/app/services
       - ./orders/templates:/app/templates