feat: add MCP server with resources, tools, auth, and Traefik routing

- Add backend/app/mcp_server.py with FastMCP server (hms-cms)
- Resources: design-rules, page-structure, sync-status
- Tools: trigger_sync, get_sync_log, set_rentman_token, read_file,
  write_file, create_page, deploy, git_commit, git_status
- Bearer token auth via MCP_AUTH_TOKEN env var
- Mount MCP at /mcp with streamable HTTP transport
- Integrate session manager in FastAPI lifespan
- Add Traefik labels for external /mcp route on hms.media-on.de
- Add git, docker.io, curl to backend Dockerfile
- Mount repo root + docker socket in backend container
- Add mcp>=1.0.0 to requirements.txt

backend/Dockerfile

@@ -2,9 +2,9 @@ FROM python:3.12-slim
 
 WORKDIR /app
 
-# Install system dependencies for asyncpg
+# Install system dependencies for asyncpg + git + docker-cli (MCP tools)
 RUN apt-get update && apt-get install -y --no-install-recommends \
-    gcc libpq-dev && \
+    gcc libpq-dev git docker.io curl && \
     rm -rf /var/lib/apt/lists/*
 
 COPY requirements.txt .