Add Claude N8N toolkit with Docker mock API server

- Added comprehensive N8N development tools collection
- Added Docker-containerized mock API server for testing
- Added complete documentation and setup guides
- Added mock API server with health checks and data endpoints
- Tools include workflow analyzers, debuggers, and controllers

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

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

claude_n8n/tools/api_data/test_data.json

@@ -0,0 +1,18 @@
+{
+  "message": "Hello from mock API",
+  "timestamp": 1749928362092,
+  "items": [
+    {
+      "id": 1,
+      "name": "Item 1"
+    },
+    {
+      "id": 2,
+      "name": "Item 2"
+    },
+    {
+      "id": 3,
+      "name": "Item 3"
+    }
+  ]
+}