fix: address code review feedback for Docker consolidation

- Improved GitHub Actions test to verify N8N_MODE environment variable
- Added explanatory comment in docker-compose.n8n.yml
- Added Docker Build Changes section to deployment documentation
- Explains the consolidation benefits and rationale for users

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

@@ -82,6 +82,7 @@ jobs:
 
       - name: Test Docker image
         run: |
+          # Test that the image starts correctly with N8N_MODE
           docker run --rm \
             -e N8N_MODE=true \
             -e MCP_MODE=http \
@@ -90,7 +91,7 @@ jobs:
             -e MCP_AUTH_TOKEN=test-token-minimum-32-chars-long \
             -e AUTH_TOKEN=test-token-minimum-32-chars-long \
             ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:latest \
-            node dist/mcp/index.js --version
+            node -e "console.log('N8N_MODE:', process.env.N8N_MODE); process.exit(0);"
 
       - name: Test health endpoint
         run: |