Add S3-backed storage to prevent data loss

- New lib/storage.mjs: async S3 backup on every queue/log save
- Versioned S3 bucket (claw-apply-data) keeps every revision
- Auto-restore from S3 if local file is missing or corrupt
- saveQueue/saveLog now validate data type before writing
  (prevents the exact bug that corrupted the queue)
- IAM role attached to EC2 instance for credential-free S3 access
- Config: storage.type = "local" (default) or "s3"

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

package.json

@@ -9,6 +9,7 @@
     "apply": "node job_applier.mjs"
   },
   "dependencies": {
+    "@aws-sdk/client-s3": "^3.700.0",
     "@onkernel/sdk": "^0.15.0",
     "playwright": "^1.40.0"
   },