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)

leantime-mcp/Dockerfile

@@ -0,0 +1,16 @@
+FROM python:3.12-slim
+
+RUN apt-get update && apt-get install -y --no-install-recommends git && rm -rf /var/lib/apt/lists/*
+
+WORKDIR /app
+
+RUN git clone https://github.com/daniel-eder/leantime-mcp.git && \
+    cd leantime-mcp && \
+    pip install --no-cache-dir fastmcp && \
+    pip install --no-cache-dir -e .
+
+WORKDIR /app/leantime-mcp
+
+EXPOSE 8079
+
+CMD ["fastmcp", "run", "src/leantime_mcp/server.py:app", "--transport", "sse", "--port", "8079", "--host", "0.0.0.0"]