chore: upgrade Docker base images to Node.js 22 LTS Alpine (v2.7.22)

- Updated all Dockerfiles from node:20-alpine to node:22-alpine
- Addresses known vulnerabilities in older Alpine images
- Provides better long-term support with Node.js 22 LTS (until April 2027)
- Updated documentation to reflect new base image version
- Tested and verified compatibility with all dependencies

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

Co-Authored-By: Claude <noreply@anthropic.com>

package.json

@@ -1,6 +1,6 @@
 {
   "name": "n8n-mcp",
-  "version": "2.7.21",
+  "version": "2.7.22",
   "description": "Integration between n8n workflow automation and Model Context Protocol (MCP)",
   "main": "dist/index.js",
   "bin": {