README: replace vague cross-app section with actual code dependencies

List specific model imports, glue services, internal APIs, and
domain events that blog code actually references.

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

README.md

@@ -43,11 +43,23 @@ shared/                 # Submodule → git.rose-ash.com/coop/shared.git
 glue/                   # Submodule → git.rose-ash.com/coop/glue.git
 ```
 
-## Cross-App Integration
+## Dependencies
 
-- **Login adoption:** When a user logs in via magic link, `auth/routes.py` emits a `user.logged_in` domain event. The glue layer's `login_handlers.py` picks it up and adopts anonymous cart items + calendar entries.
-- **Cart widget:** Context processor fetches cart summary via `internal_api.get("cart", "/internal/cart/summary")`.
-- **Internal API:** `/internal/coop/` endpoints serve blog data to other apps.
+**Cross-app model imports:**
+- `events.models.calendars.Calendar` — post routes and Ghost sync use calendars attached to pages
+- `market.models.market_place.MarketPlace` — post admin manages marketplaces on pages
+- `cart.models.page_config.PageConfig` — post admin manages per-page SumUp config
+
+**Glue services:**
+- `glue.services.navigation.get_navigation_tree` — context processor builds site nav
+- `glue.services.relationships.attach_child / detach_child` — post admin attaches/detaches calendars and marketplaces to pages
+
+**Internal APIs:**
+- Calls `GET /internal/cart/summary` — context processor for cart widget
+- Exposes `/internal/coop/*` — serves blog data to other apps
+
+**Domain events:**
+- `auth/routes.py` emits `user.logged_in` via `shared.events.emit_event`
 
 ## Running