Add create_marketplace() and soft_delete_marketplace() to MarketService
protocol, SQL implementation, and stubs — centralises market CRUD that
was previously duplicated in blog and events app-level service files.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Add typed service contracts (Protocols + frozen DTOs) in shared/contracts/
for cross-domain communication. Each domain exposes a service interface
(BlogService, CalendarService, MarketService, CartService) backed by SQL
implementations in shared/services/. A singleton registry with has() guards
enables composable startup — apps register their own domain service and
stubs for absent domains.
Absorbs glue layer: navigation, relationships, event handlers (login,
container, order) now live in shared/ with has()-guarded service calls.
Factory gains domain_services_fn parameter for per-app service registration.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
