feat(integrations): add n8n community node for Mem0

A programmatic n8n community node wrapping the hosted Mem0 v3 REST API:
add, search, get, get-many, update, delete, plus usableAsTool so the n8n
AI Agent can call it.

- Zero runtime dependencies (calls REST directly), TypeScript, ESLint clean —
  meets n8n verified-node requirements
- Add supports custom_instructions, custom_categories, includes, excludes,
  a client-side entity-id guard, and async event polling (itemIndex on errors)
- Anonymous opt-out telemetry (MEM0_TELEMETRY=false)
- Docs page + docs.json/llms.txt entry, ci-gate + release wiring, AGENTS.md rows
- Verified: tsc + ESLint + live E2E (add → search → get → delete) vs api.mem0.ai

Split out of #6057 per review (separate PRs per integration).

integrations/n8n-nodes-mem0/credentials/Mem0Api.credentials.ts

@@ -0,0 +1,53 @@
+import {
+	IAuthenticateGeneric,
+	ICredentialTestRequest,
+	ICredentialType,
+	INodeProperties,
+} from 'n8n-workflow';
+
+export class Mem0Api implements ICredentialType {
+	name = 'mem0Api';
+
+	displayName = 'Mem0 API';
+
+	documentationUrl = 'https://docs.mem0.ai/platform/quickstart';
+
+	properties: INodeProperties[] = [
+		{
+			displayName: 'API Key',
+			name: 'apiKey',
+			type: 'string',
+			typeOptions: { password: true },
+			default: '',
+			required: true,
+			description: 'Your Mem0 API key (starts with "m0-"). Create one at app.mem0.ai → Settings → API Keys.',
+		},
+		{
+			displayName: 'Base URL',
+			name: 'baseUrl',
+			type: 'string',
+			default: 'https://api.mem0.ai',
+			description: 'Mem0 API base URL. Override only for self-hosted or non-default deployments.',
+		},
+	];
+
+	// Injects "Authorization: Token <apiKey>" on every request, matching the
+	// scheme used by Mem0's official SDKs (Authorization: Token m0-...).
+	authenticate: IAuthenticateGeneric = {
+		type: 'generic',
+		properties: {
+			headers: {
+				Authorization: '=Token {{$credentials.apiKey}}',
+			},
+		},
+	};
+
+	// Cheap authenticated GET; validates the key when the user clicks "Test".
+	test: ICredentialTestRequest = {
+		request: {
+			baseURL: '={{$credentials.baseUrl}}',
+			url: '/v1/ping/',
+			method: 'GET',
+		},
+	};
+}