PR-002: Persistence Adapters — in-memory, zero external dependencies

- Repository interfaces defined by domain (@landvex/domain)
- 6 in-memory adapters: Session, Mission, DecisionCase, Artifact, EventStore, UnitOfWork
- 9 tests verifying adapter contracts
- Domain unchanged — infrastructure depends on domain, never reverse
- ADR-006: In-Memory Adapters for Testing

Definition of Done met:
- All adapters compile against domain interfaces
- Unit tests pass (9/9)
- No PostgreSQL, S3, Express, AI in this PR
- Ready for PR-003: PostgreSQL adapters

packages/infrastructure/README.md

@@ -0,0 +1,53 @@
+# @landvex/infrastructure
+
+Persistence adapters and infrastructure for LandveX domain.
+
+## Architecture
+
+```
+Domain (interfaces) ← Infrastructure (adapters)
+```
+
+- **Domain defines** repository interfaces (WHAT)
+- **Infrastructure implements** them (HOW)
+- **Domain never depends** on infrastructure
+
+## Repository Interfaces
+
+| Interface | Purpose |
+|-----------|---------|
+| `FieldSessionRepository` | Store/retrieve field sessions |
+| `MissionRepository` | Store/retrieve missions |
+| `DecisionCaseRepository` | Store/retrieve decision cases |
+| `ArtifactRegistry` | Register/find artifacts |
+| `EventStore` | Append-only event log |
+| `UnitOfWork` | Coordinate multiple repositories |
+
+## In-Memory Adapters
+
+For testing and development:
+
+| Adapter | Data Structure |
+|---------|---------------|
+| `InMemoryFieldSessionRepository` | Map<string, FieldSession> |
+| `InMemoryMissionRepository` | Map<string, Mission> |
+| `InMemoryDecisionCaseRepository` | Map<string, DecisionCase> |
+| `InMemoryArtifactRegistry` | Map<string, Artifact> |
+| `InMemoryEventStore` | Array<DomainEvent> |
+| `InMemoryUnitOfWork` | Coordinates all above |
+
+## Future Adapters
+
+| Adapter | Technology | Status |
+|---------|-----------|--------|
+| PostgreSQL repositories | PostgreSQL | Planned |
+| S3 Artifact Registry | AWS S3 / Cloudflare R2 | Planned |
+| Event Store | PostgreSQL / EventStoreDB | Planned |
+
+## ADRs
+
+- ADR-006: In-Memory Adapters for Testing
+
+## Dependencies
+
+- `@landvex/domain` — repository interfaces depend on domain types