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_entries/routes.py

@@ -216,7 +216,49 @@ def register():
         if ident["session_id"] is not None:
             frag_params["session_id"] = ident["session_id"]
 
-        html = await render_template("_types/day/_main_panel.html")
+        # Re-query day entries for the sexp component
+        from datetime import date as date_cls, timedelta
+        from bp.calendar.services import get_visible_entries_for_period
+        from quart import session as qsession
+
+        period_start = datetime(year, month, day, tzinfo=timezone.utc)
+        period_end = period_start + timedelta(days=1)
+        user = getattr(g, "user", None)
+        session_id = qsession.get("calendar_sid")
+
+        visible = await get_visible_entries_for_period(
+            sess=g.s,
+            calendar_id=g.calendar.id,
+            period_start=period_start,
+            period_end=period_end,
+            user=user,
+            session_id=session_id,
+        )
+
+        # Query day slots for this weekday
+        day_date = date_cls(year, month, day)
+        weekday_attr = ["mon","tue","wed","thu","fri","sat","sun"][day_date.weekday()]
+        stmt = select(CalendarSlot).where(
+            CalendarSlot.calendar_id == g.calendar.id,
+            getattr(CalendarSlot, weekday_attr) == True,
+            CalendarSlot.deleted_at.is_(None),
+        ).order_by(CalendarSlot.time_start.asc(), CalendarSlot.id.asc())
+        result = await g.s.execute(stmt)
+        day_slots = list(result.scalars())
+
+        styles = getattr(g, "styles", None) or {}
+        ctx = {
+            "calendar": g.calendar,
+            "day_entries": visible.merged_entries,
+            "day": day,
+            "month": month,
+            "year": year,
+            "hx_select_search": "#main-panel",
+            "styles": styles,
+        }
+
+        from sexp.sexp_components import render_day_main_panel
+        html = render_day_main_panel(ctx)
         mini_html = await fetch_fragment("cart", "cart-mini", params=frag_params, required=False)
         return await make_response(html + mini_html, 200)