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/package.json

@@ -0,0 +1,22 @@
+{
+  "name": "@landvex/infrastructure",
+  "version": "0.1.0",
+  "description": "Persistence adapters and infrastructure for LandveX domain",
+  "main": "dist/index.js",
+  "types": "dist/index.d.ts",
+  "scripts": {
+    "build": "tsc",
+    "test": "jest",
+    "test:watch": "jest --watch"
+  },
+  "dependencies": {
+    "@landvex/domain": "file:../domain"
+  },
+  "devDependencies": {
+    "@types/jest": "^29.5.0",
+    "@types/node": "^20.0.0",
+    "jest": "^29.5.0",
+    "ts-jest": "^29.1.0",
+    "typescript": "^5.3.0"
+  }
+}