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/credentials/Mem0Api.credentials.ts

@@ -1,5 +1,6 @@
 import {
 	IAuthenticateGeneric,
+	Icon,
 	ICredentialTestRequest,
 	ICredentialType,
 	INodeProperties,
@@ -10,6 +11,8 @@ export class Mem0Api implements ICredentialType {
 
 	displayName = 'Mem0 API';
 
+	icon: Icon = 'file:mem0.svg';
+
 	documentationUrl = 'https://docs.mem0.ai/platform/quickstart';
 
 	properties: INodeProperties[] = [