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/post/services/markets.py

@@ -7,10 +7,10 @@ from sqlalchemy import select
 from sqlalchemy.ext.asyncio import AsyncSession
 
 from shared.models.market_place import MarketPlace
-from models.ghost_content import Post
 from shared.models.page_config import PageConfig
 from shared.browser.app.utils import utcnow
-from glue.services.relationships import attach_child, detach_child
+from shared.services.registry import services
+from shared.services.relationships import attach_child, detach_child
 
 
 class MarketError(ValueError):
@@ -36,7 +36,7 @@ async def create_market(sess: AsyncSession, post_id: int, name: str) -> MarketPl
         raise MarketError("Market name must not be empty.")
     slug = slugify(name)
 
-    post = (await sess.execute(select(Post).where(Post.id == post_id))).scalar_one_or_none()
+    post = await services.blog.get_post_by_id(sess, post_id)
     if not post:
         raise MarketError(f"Post {post_id} does not exist.")
 
@@ -71,13 +71,16 @@ async def create_market(sess: AsyncSession, post_id: int, name: str) -> MarketPl
 
 
 async def soft_delete_market(sess: AsyncSession, post_slug: str, market_slug: str) -> bool:
+    post = await services.blog.get_post_by_slug(sess, post_slug)
+    if not post:
+        return False
+
     market = (
         await sess.execute(
             select(MarketPlace)
-            .join(Post, MarketPlace.container_id == Post.id)
-            .where(MarketPlace.container_type == "page")
             .where(
-                Post.slug == post_slug,
+                MarketPlace.container_type == "page",
+                MarketPlace.container_id == post.id,
                 MarketPlace.slug == market_slug,
                 MarketPlace.deleted_at.is_(None),
             )