Prevents SQLAlchemy 'table already defined' error if the table gets
registered by a stale glue submodule or cached Docker layer before
the shared model is loaded.
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>
