Initial implementation of n8n MCP server

Implements Hybrid MCP Light pattern with:
- 5 curated tools: list_workflows, get_workflow, list_executions, get_execution, trigger_webhook
- API pass-through tool: n8n_api_call for complete coverage
- API reference resource: n8n://api-reference
- Dockerfile and CI workflow for Gitea container registry

docker-compose.yml

@@ -0,0 +1,16 @@
+services:
+  n8n-mcp:
+    image: gitea.ext.ben.io/b3nw/n8n-mcp-custom:latest
+    container_name: n8n-mcp
+    restart: unless-stopped
+    ports:
+      - "${PORT:-8000}:8000"
+    environment:
+      - N8N_URL=${N8N_URL}
+      - N8N_API_KEY=${N8N_API_KEY}
+    healthcheck:
+      test: ["CMD", "curl", "-f", "http://localhost:8000/health"]
+      interval: 30s
+      timeout: 10s
+      retries: 3
+      start_period: 5s