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>

.github/workflows/docker-build-n8n.yml

@@ -0,0 +1,145 @@
+name: Build and Publish n8n Docker Image
+
+on:
+  push:
+    branches:
+      - main
+    tags:
+      - 'v*'
+  pull_request:
+    branches:
+      - main
+  workflow_dispatch:
+
+env:
+  REGISTRY: ghcr.io
+  IMAGE_NAME: ${{ github.repository }}/n8n-mcp
+
+jobs:
+  build-and-push:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      packages: write
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Log in to GitHub Container Registry
+        if: github.event_name != 'pull_request'
+        uses: docker/login-action@v3
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Extract metadata
+        id: meta
+        uses: docker/metadata-action@v5
+        with:
+          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
+          tags: |
+            type=ref,event=branch
+            type=ref,event=pr
+            type=semver,pattern={{version}}
+            type=semver,pattern={{major}}.{{minor}}
+            type=raw,value=latest,enable={{is_default_branch}}
+
+      - name: Build and push Docker image
+        uses: docker/build-push-action@v5
+        with:
+          context: .
+          file: ./Dockerfile.n8n
+          push: ${{ github.event_name != 'pull_request' }}
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}
+          cache-from: type=gha
+          cache-to: type=gha,mode=max
+          platforms: linux/amd64,linux/arm64
+
+  test-image:
+    needs: build-and-push
+    runs-on: ubuntu-latest
+    if: github.event_name != 'pull_request'
+    permissions:
+      contents: read
+      packages: read
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Log in to GitHub Container Registry
+        uses: docker/login-action@v3
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Test Docker image
+        run: |
+          docker run --rm \
+            -e N8N_MODE=true \
+            -e N8N_API_URL=http://localhost:5678 \
+            -e N8N_API_KEY=test \
+            -e MCP_AUTH_TOKEN=test \
+            ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:latest \
+            node dist/index.js n8n --version
+
+      - name: Test health endpoint
+        run: |
+          # Start container in background
+          docker run -d \
+            --name n8n-mcp-test \
+            -p 3000:3000 \
+            -e N8N_MODE=true \
+            -e N8N_API_URL=http://localhost:5678 \
+            -e N8N_API_KEY=test \
+            -e MCP_AUTH_TOKEN=test \
+            ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:latest
+          
+          # Wait for container to start
+          sleep 10
+          
+          # Test health endpoint
+          curl -f http://localhost:3000/health || exit 1
+          
+          # Cleanup
+          docker stop n8n-mcp-test
+          docker rm n8n-mcp-test
+
+  create-release:
+    needs: [build-and-push, test-image]
+    runs-on: ubuntu-latest
+    if: startsWith(github.ref, 'refs/tags/v')
+    permissions:
+      contents: write
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Create Release
+        uses: softprops/action-gh-release@v1
+        with:
+          generate_release_notes: true
+          body: |
+            ## Docker Image
+
+            The n8n-specific Docker image is available at:
+            ```
+            docker pull ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:${{ github.ref_name }}
+            ```
+
+            ## Quick Deploy
+
+            Use the quick deploy script for easy setup:
+            ```bash
+            ./deploy/quick-deploy-n8n.sh setup
+            ```
+
+            See the [deployment documentation](https://github.com/${{ github.repository }}/blob/main/docs/deployment-n8n.md) for detailed instructions.