chore: update n8n to 2.1.4 and bump version to 2.31.2 (#507)

- Updated n8n from 2.0.2 to 2.1.4
- Updated n8n-core from 2.0.1 to 2.1.3
- Updated n8n-workflow from 2.0.1 to 2.1.1
- Updated @n8n/n8n-nodes-langchain from 2.0.1 to 2.1.3
- Rebuilt node database with 540 nodes (434 from n8n-nodes-base, 106 from @n8n/n8n-nodes-langchain)
- Refreshed template database with 2,737 workflow templates from n8n.io
- Updated README badge with new n8n version
- Updated CHANGELOG with dependency changes

Conceived by Romuald Członkowski - https://www.aiadvisors.pl/en

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Romuald Członkowski <romualdczlonkowski@MacBook-Pro-Romuald.local>
Co-authored-by: Claude <noreply@anthropic.com>

README.md

@@ -5,7 +5,7 @@
 [![npm version](https://img.shields.io/npm/v/n8n-mcp.svg)](https://www.npmjs.com/package/n8n-mcp)
 [![codecov](https://codecov.io/gh/czlonkowski/n8n-mcp/graph/badge.svg?token=YOUR_TOKEN)](https://codecov.io/gh/czlonkowski/n8n-mcp)
 [![Tests](https://img.shields.io/badge/tests-3336%20passing-brightgreen.svg)](https://github.com/czlonkowski/n8n-mcp/actions)
-[![n8n version](https://img.shields.io/badge/n8n-2.0.2-orange.svg)](https://github.com/n8n-io/n8n)
+[![n8n version](https://img.shields.io/badge/n8n-2.1.4-orange.svg)](https://github.com/n8n-io/n8n)
 [![Docker](https://img.shields.io/badge/docker-ghcr.io%2Fczlonkowski%2Fn8n--mcp-green.svg)](https://github.com/czlonkowski/n8n-mcp/pkgs/container/n8n-mcp)
 [![Deploy on Railway](https://railway.com/button.svg)](https://railway.com/deploy/n8n-mcp?referralCode=n8n-mcp)