feat(auth): Stage 8C - authentication foundation
- Add KcUser/KcUserRole domain models with copyWith, equality, toString
- Add AuthState sealed hierarchy (unauthenticated, loading, authenticated, error)
- Add AuthService abstract contract (signIn, signOut, refreshSession, stream)
- Add AuthException with optional HTTP statusCode
- Add CredentialStore abstract contract with CredentialKeys constants
- Add InMemoryCredentialStore implementation
- Add FakeAuthService with role-based sign-in simulation
- Add KcAppEnvironment.square to core enum with SQ label
- Add KcBootstrap square case (falls back to fake until Stage 10A)
- Update kell_web and kell_mobile shell environment badges for square case
- Add integrations dependency to kell_web and kell_mobile pubspec.yaml
- Add auth to run_all_tests.sh TESTABLE and ANALYZABLE lists
- Add 42 auth tests (42/42 passing)
- Add 1 new core test for square bootstrap fallback (21/21 passing)
- Update master_development_brief.md: Stage 8C complete, Stage 8 complete
- Total: 764/764 tests passing, dart analyze clean
Stage 8 (infrastructure package activation) is now complete.
Next: feat/wc-orders-integration (Stage 9A)
Mike Kell
bda93640e4