Domain isolation: replace cross-domain imports with service calls

Replace direct Calendar, MarketPlace, and Post model queries with typed
service calls (services.blog, services.calendar, services.market,
services.cart). Blog registers all 4 services via domain_services_fn
with has() guards for composable deployment.

Key changes:
- app.py: use domain_services_fn instead of inline service registration
- admin routes: MarketPlace queries → services.market.marketplaces_for_container()
- entry_associations: CalendarEntryPost → services.calendar.entry_ids_for_content()
- markets service: Post query → services.blog.get_post_by_id/slug()
- posts_data, post routes: use calendar/market/cart services
- menu_items: glue imports → shared imports

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

bp/blog/services/posts_data.py

@@ -1,7 +1,7 @@
 from ..ghost_db import DBClient  # adjust import path
 from sqlalchemy import select
 from models.ghost_content import PostLike
-from shared.models.calendars import CalendarEntry, CalendarEntryPost
+from shared.services.registry import services
 from quart import g
 
 async def posts_data(
@@ -85,29 +85,8 @@ async def posts_data(
       for post in posts:
           post["is_liked"] = False
 
-  # Fetch associated entries for each post
-  # Get all confirmed entries associated with these posts
-  from sqlalchemy.orm import selectinload
-  entries_result = await session.execute(
-      select(CalendarEntry, CalendarEntryPost.content_id)
-      .join(CalendarEntryPost, CalendarEntry.id == CalendarEntryPost.entry_id)
-      .options(selectinload(CalendarEntry.calendar))  # Eagerly load calendar
-      .where(
-          CalendarEntryPost.content_type == "post",
-          CalendarEntryPost.content_id.in_(post_ids),
-          CalendarEntryPost.deleted_at.is_(None),
-          CalendarEntry.deleted_at.is_(None),
-          CalendarEntry.state == "confirmed"
-      )
-      .order_by(CalendarEntry.start_at.asc())
-  )
-
-  # Group entries by post_id
-  entries_by_post = {}
-  for entry, post_id in entries_result:
-      if post_id not in entries_by_post:
-          entries_by_post[post_id] = []
-      entries_by_post[post_id].append(entry)
+  # Fetch associated entries for each post via calendar service
+  entries_by_post = await services.calendar.confirmed_entries_for_posts(session, post_ids)
 
   # Add associated_entries to each post
   for post in posts: