feat: integrate Leantime project management via MCP (leantime-mcp + MCPO)
- Add leantime-mcp Dockerfile (daniel-eder/leantime-mcp, SSE transport)
- Add leantime-mcp service to docker-compose.yml on effi-net
- Add Leantime env vars to .env.example (API_KEY, USER_EMAIL, URL)
- Update services.md: Leantime + leantime-mcp entries, dependency diagram, resource table
- Update mcp-et-n8n.md: MCPO config with leantime SSE server, new leantime-mcp section
- Add LEANTIME-INSTALLATION.md: full reinstall guide (XPenology + MCP)