fix(n8n): address review feedback and pass the verification scanner

- Telemetry: replace client-side PostHog (which read process.env, banned in
  verified nodes) with first-party `source: "N8N"` attribution on API requests,
  mirroring OpenClaw. Removes the undisclosed-collection concern entirely.
- Verification-scanner fixes: add credential icon, use NodeConnectionTypes.Main
  instead of the 'main' literal, wrap error paths in NodeApiError, stop shipping
  .d.ts / tsbuildinfo, and align the local eslint config with the scanner.
- Add offline unit tests (jest): entity-id guard, JSON-parse errors, poll-timeout
  loop, source attribution, and Return All pagination.
- Get Many: add a Return All option that pages through all memories.
- Docs: README telemetry note and an AGENTS.md Key Directories row.

Verified: build + tsc + eslint + 5 unit tests + live E2E against api.mem0.ai, and
the packed tarball passes @n8n/scan-community-package with zero violations.

integrations/n8n-nodes-mem0/package.json

@@ -31,6 +31,7 @@
     "format": "prettier nodes credentials --write",
     "lint": "eslint nodes credentials package.json",
     "lintfix": "eslint nodes credentials package.json --fix",
+    "test": "jest",
     "prepublishOnly": "npm run build && npm run lint"
   },
   "files": [
@@ -46,14 +47,17 @@
     ]
   },
   "devDependencies": {
+    "@types/jest": "^29.5.14",
     "@types/node": "^20.0.0",
     "@typescript-eslint/parser": "^8.0.0",
     "eslint": "^8.57.0",
+    "jest": "^29.7.0",
     "eslint-plugin-n8n-nodes-base": "^1.16.3",
     "gulp": "^5.0.0",
     "n8n-workflow": "*",
     "prettier": "^3.3.0",
     "rimraf": "^5.0.0",
+    "ts-jest": "^29.2.5",
     "typescript": "^5.5.0"
   },
   "peerDependencies": {