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/src/adapters/in-memory-session-repository.ts

@@ -0,0 +1,50 @@
+/**
+ * In-Memory FieldSession Repository
+ *
+ * Adapter: Implements FieldSessionRepository using a Map.
+ * Purpose: Testing, development, CI/CD pipelines.
+ * NOT for production.
+ *
+ * ADR-006: In-memory adapters for testing
+ * - Fast, isolated, no external dependencies
+ * - Reset between tests
+ * - Never used in production
+ */
+
+import {
+  FieldSession,
+  SessionId,
+} from '@landvex/domain';
+import { FieldSessionRepository } from '../repositories/repository-interfaces';
+
+export class InMemoryFieldSessionRepository implements FieldSessionRepository {
+  private sessions = new Map<string, FieldSession>();
+
+  async save(session: FieldSession): Promise<void> {
+    this.sessions.set(session.id, session);
+  }
+
+  async findById(id: SessionId): Promise<FieldSession | null> {
+    return this.sessions.get(id) ?? null;
+  }
+
+  async findActive(): Promise<FieldSession[]> {
+    return Array.from(this.sessions.values())
+      .filter(s => s.status === 'planned' || s.status === 'active');
+  }
+
+  async findByDateRange(start: Date, end: Date): Promise<FieldSession[]> {
+    return Array.from(this.sessions.values())
+      .filter(s => s.date >= start && s.date <= end);
+  }
+
+  /** Reset for testing */
+  clear(): void {
+    this.sessions.clear();
+  }
+
+  /** Count for assertions */
+  count(): number {
+    return this.sessions.size;
+  }
+}