Decouple all cross-app service calls to HTTP endpoints

Replace every direct cross-app services.* call with HTTP-based
communication: call_action() for writes, fetch_data() for reads.
Each app now registers only its own domain service.

Infrastructure:
- shared/infrastructure/actions.py — POST client for /internal/actions/
- shared/infrastructure/data_client.py — GET client for /internal/data/
- shared/contracts/dtos.py — dto_to_dict/dto_from_dict serialization

Action endpoints (writes):
- events: 8 handlers (ticket adjust, claim/confirm, toggle, adopt)
- market: 2 handlers (create/soft-delete marketplace)
- cart: 1 handler (adopt cart for user)

Data endpoints (reads):
- blog: 4 (post-by-slug/id, posts-by-ids, search-posts)
- events: 10 (pending entries/tickets, entries/tickets for page/order,
  entry-ids, associated-entries, calendars, visible-entries-for-period)
- market: 1 (marketplaces-for-container)
- cart: 1 (cart-summary)

Service registration cleanup:
- blog→blog+federation, events→calendar+federation,
  market→market+federation, cart→cart only,
  federation→federation only, account→nothing
- Stubs reduced to minimal StubFederationService

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

cart/bp/cart/global_routes.py

@@ -8,7 +8,7 @@ from sqlalchemy import select
 from shared.models.market import CartItem
 from shared.models.order import Order
 from shared.models.market_place import MarketPlace
-from shared.services.registry import services
+from shared.infrastructure.actions import call_action
 from .services import (
     current_cart_identity,
     get_cart,
@@ -91,13 +91,12 @@ def register(url_prefix: str) -> Blueprint:
         tt_raw = (form.get("ticket_type_id") or "").strip()
         ticket_type_id = int(tt_raw) if tt_raw else None
 
-        await services.calendar.adjust_ticket_quantity(
-            g.s, entry_id, count,
-            user_id=ident["user_id"],
-            session_id=ident["session_id"],
-            ticket_type_id=ticket_type_id,
-        )
-        await g.s.flush()
+        await call_action("events", "adjust-ticket-quantity", payload={
+            "entry_id": entry_id, "count": count,
+            "user_id": ident["user_id"],
+            "session_id": ident["session_id"],
+            "ticket_type_id": ticket_type_id,
+        })
 
         resp = await make_response("", 200)
         resp.headers["HX-Refresh"] = "true"
@@ -256,13 +255,17 @@ def register(url_prefix: str) -> Blueprint:
 
         # Resolve page/market slugs so product links render correctly
         if order.page_config:
-            post = await services.blog.get_post_by_id(g.s, order.page_config.container_id)
+            from shared.infrastructure.data_client import fetch_data
+            from shared.contracts.dtos import CalendarEntryDTO, TicketDTO, dto_from_dict
+            post = await fetch_data("blog", "post-by-id",
+                                    params={"id": order.page_config.container_id},
+                                    required=False)
             if post:
-                g.page_slug = post.slug
+                g.page_slug = post["slug"]
                 result = await g.s.execute(
                     select(MarketPlace).where(
                         MarketPlace.container_type == "page",
-                        MarketPlace.container_id == post.id,
+                        MarketPlace.container_id == post["id"],
                         MarketPlace.deleted_at.is_(None),
                     ).limit(1)
                 )
@@ -278,8 +281,14 @@ def register(url_prefix: str) -> Blueprint:
 
         status = (order.status or "pending").lower()
 
-        calendar_entries = await services.calendar.get_entries_for_order(g.s, order.id)
-        order_tickets = await services.calendar.get_tickets_for_order(g.s, order.id)
+        from shared.infrastructure.data_client import fetch_data
+        from shared.contracts.dtos import CalendarEntryDTO, TicketDTO, dto_from_dict
+        raw_entries = await fetch_data("events", "entries-for-order",
+                                       params={"order_id": order.id}, required=False) or []
+        calendar_entries = [dto_from_dict(CalendarEntryDTO, e) for e in raw_entries]
+        raw_tickets = await fetch_data("events", "tickets-for-order",
+                                       params={"order_id": order.id}, required=False) or []
+        order_tickets = [dto_from_dict(TicketDTO, t) for t in raw_tickets]
         await g.s.flush()
 
         html = await render_template(