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/jest.config.js

@@ -0,0 +1,10 @@
+/** Jest config lives here (not in package.json) so the published package.json
+ * stays minimal for the n8n verification scanner. This file is dev-only; it is
+ * not shipped (see the `files` field in package.json). */
+module.exports = {
+	testEnvironment: 'node',
+	testMatch: ['**/test/**/*.test.ts'],
+	transform: {
+		'^.+\\.tsx?$': ['ts-jest', {}],
+	},
+};