chore: switch to MIT license for wider adoption (v2.4.0)

- Changed from Sustainable Use License to MIT License
- Added attribution to Romuald Czlonkowski @ www.aiadvisors.pl/en
- Created ATTRIBUTION.md with easy attribution examples
- Updated package.json, README.md, and CLAUDE.md
- Added GitHub stars badge to encourage community support
- Bumped version to 2.4.0 to mark this significant change

This change allows:
✅ Unrestricted use in personal and commercial projects
✅ Easy integration into corporate environments
✅ Freedom to modify and distribute
✅ Hosting as a service without restrictions

The project remains focused on helping n8n builders work more efficiently.

🤖 Generated with Claude Code

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

package.json

@@ -1,6 +1,6 @@
 {
   "name": "n8n-mcp",
-  "version": "2.3.3",
+  "version": "2.4.0",
   "description": "Integration between n8n workflow automation and Model Context Protocol (MCP)",
   "main": "dist/index.js",
   "scripts": {
@@ -38,8 +38,8 @@
     "workflow",
     "automation"
   ],
-  "author": "AiAdvisors Romuald Czlonkowski",
-  "license": "Sustainable-Use-1.0",
+  "author": "Romuald Czlonkowski @ www.aiadvisors.pl/en",
+  "license": "MIT",
   "bugs": {
     "url": "https://github.com/czlonkowski/n8n-mcp/issues"
   },