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>

blog/bp/post/routes.py

@@ -2,7 +2,6 @@ from __future__ import annotations
 
 
 from quart import (
-    render_template,
     make_response,
     g,
     Blueprint,
@@ -115,7 +114,7 @@ def register():
   @cache_page(tag="post.post_detail")
   async def post_detail(slug: str):
     from shared.sexp.page import get_template_context
-    from sexp_components import render_post_page, render_post_oob
+    from sexp.sexp_components import render_post_page, render_post_oob
 
     tctx = await get_template_context()
     if not is_htmx_request():
@@ -129,16 +128,13 @@ def register():
   @clear_cache(tag="post.post_detail", tag_scope="user")
   async def like_toggle(slug: str):
       from shared.utils import host_url
+      from sexp.sexp_components import render_like_toggle_button
+
+      like_url = host_url(url_for('blog.post.like_toggle', slug=slug))
 
       # Get post_id from g.post_data
       if not g.user:
-          html = await render_template(
-              "_types/browse/like/button.html",
-              slug=slug,
-              liked=False,
-              like_url=host_url(url_for('blog.post.like_toggle', slug=slug)),
-              item_type='post',
-          )
+          html = render_like_toggle_button(slug, False, like_url)
           resp = make_response(html, 403)
           return resp
 
@@ -150,13 +146,7 @@ def register():
       })
       liked = result["liked"]
 
-      html = await render_template(
-          "_types/browse/like/button.html",
-          slug=slug,
-          liked=liked,
-          like_url=host_url(url_for('blog.post.like_toggle', slug=slug)),
-          item_type='post',
-      )
+      html = render_like_toggle_button(slug, liked, like_url)
       return html
 
   @bp.get("/w/<widget_domain>/")