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

.env.example

@@ -2,6 +2,3 @@
 KOMODO_URL=https://komodo.example.com
 KOMODO_API_KEY=your-api-key
 KOMODO_API_SECRET=your-api-secret
-
-# MCP Transport Security (optional)
-MCP_ALLOWED_HOSTS=localhost:*,127.0.0.1:*