feat: add n8n integration with MCP Client Tool support

- Add N8N_MODE environment variable for n8n-specific behavior
- Implement HTTP Streamable transport with multiple session support
- Add protocol version endpoint (GET /mcp) for n8n compatibility
- Support multiple initialize requests for stateless n8n clients
- Add Docker configuration for n8n deployment
- Add test script with persistent volume support
- Add comprehensive unit tests for n8n mode
- Fix session management to handle per-request transport pattern

BREAKING CHANGE: Server now creates new transport for each initialize request
when running in n8n mode to support n8n's stateless client architecture

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

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

package-lock.json

@@ -1,17 +1,16 @@
 {
   "name": "n8n-mcp",
-  "version": "2.8.1",
+  "version": "2.8.3",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "n8n-mcp",
-      "version": "2.8.1",
+      "version": "2.8.3",
       "license": "MIT",
       "dependencies": {
         "@modelcontextprotocol/sdk": "^1.13.2",
         "@n8n/n8n-nodes-langchain": "^1.103.1",
-        "axios": "^1.10.0",
         "dotenv": "^16.5.0",
         "express": "^5.1.0",
         "n8n": "^1.104.1",
@@ -33,6 +32,7 @@
         "@vitest/coverage-v8": "^3.2.4",
         "@vitest/runner": "^3.2.4",
         "@vitest/ui": "^3.2.4",
+        "axios": "^1.11.0",
         "axios-mock-adapter": "^2.1.0",
         "fishery": "^2.3.1",
         "msw": "^2.10.4",
@@ -15048,13 +15048,13 @@
       "license": "MIT"
     },
     "node_modules/axios": {
-      "version": "1.10.0",
-      "resolved": "https://registry.npmjs.org/axios/-/axios-1.10.0.tgz",
-      "integrity": "sha512-/1xYAC4MP/HEG+3duIhFr4ZQXR4sQXOIe+o6sdqzeykGLx6Upp/1p8MHqhINOvGeP7xyNHe7tsiJByc4SSVUxw==",
+      "version": "1.11.0",
+      "resolved": "https://registry.npmjs.org/axios/-/axios-1.11.0.tgz",
+      "integrity": "sha512-1Lx3WLFQWm3ooKDYZD1eXmoGO9fxYQjrycfHFC8P0sCfQVXyROp0p9PFWBehewBOdCwHc+f/b8I0fMto5eSfwA==",
       "license": "MIT",
       "dependencies": {
         "follow-redirects": "^1.15.6",
-        "form-data": "^4.0.0",
+        "form-data": "^4.0.4",
         "proxy-from-env": "^1.1.0"
       }
     },
@@ -18426,9 +18426,9 @@
       }
     },
     "node_modules/form-data": {
-      "version": "4.0.3",
-      "resolved": "https://registry.npmjs.org/form-data/-/form-data-4.0.3.tgz",
-      "integrity": "sha512-qsITQPfmvMOSAdeyZ+12I1c+CKSstAFAwu+97zrnWAbIr5u8wfsExUzCesVLC8NgHuRUqNN4Zy6UPWUTRGslcA==",
+      "version": "4.0.4",
+      "resolved": "https://registry.npmjs.org/form-data/-/form-data-4.0.4.tgz",
+      "integrity": "sha512-KrGhL9Q4zjj0kiUt5OO4Mr/A/jlI2jDYs5eHBpYHPcBEVSiipAvn2Ko2HnPe20rmcuuvMHNdZFp+4IlGTMF0Ow==",
       "license": "MIT",
       "dependencies": {
         "asynckit": "^0.4.0",