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>