feat: add /health endpoint and switch to fastmcp 2.0

- Switch from mcp package to fastmcp>=2.0 for Streamable HTTP support
  - Fixes 405 Method Not Allowed for MCP clients like Gemini CLI
  - MCP endpoint now at /mcp (POST) instead of /sse (GET)
  - Removes MCP_ALLOWED_HOSTS (handled at reverse proxy level)

- Add /health endpoint for Docker health checks
  - Returns {"status": "ok"} (200) or {"status": "degraded"} (503)
  - Enables health checks without transport security issues

- Add curl to Docker image for health checks
- Add healthcheck config to docker-compose files
- Add test-health and test-mcp Makefile targets
- Update documentation

pyproject.toml

@@ -3,10 +3,9 @@ name = "komodo-mcp"
 version = "0.1.0"
 description = "MCP Server for Komodo Docker Management"
 dependencies = [
-    "mcp",
+    "fastmcp>=2.0",
     "httpx",
     "uvicorn",
-    "fastapi",
     "python-dotenv",
 ]
 requires-python = ">=3.11"