PR-003A: PostgreSQL Repository Adapters + Persistence Independence Test

- 4 PostgreSQL adapter stubs (Session, Mission, DecisionCase, Artifact)
- Migration 001: Initial schema (sessions, missions, artifacts, decision_cases)
- Persistence Independence Test: 6 tests verifying same behavior
  across InMemory and PostgreSQL implementations
- ADR-008: PostgreSQL Adapters for Production
- ADR-009: Persistence Independence

Architecture Quality Gates:
- Domain unchanged
- Application unchanged
- Only adapter implementation changes
- Same test suite runs against both implementations

Next: PR-003B — Schema & Migrations, PR-003C — Integration Tests,
PR-003D — Unit of Work / Transactions

packages/infrastructure/src/index.ts

@@ -27,3 +27,12 @@ export { InMemoryDecisionCaseRepository } from './adapters/in-memory-decision-ca
 export { InMemoryArtifactRegistry } from './adapters/in-memory-artifact-registry';
 export { InMemoryEventStore } from './adapters/in-memory-event-store';
 export { InMemoryUnitOfWork } from './adapters/in-memory-unit-of-work';
+
+// PostgreSQL adapters (for production)
+export {
+  PostgresFieldSessionRepository,
+  PostgresMissionRepository,
+  PostgresDecisionCaseRepository,
+  PostgresArtifactRegistry,
+  PostgresConfig,
+} from './adapters/postgresql';