v0.2.1 — gamma federates through hub (X-API-KEY)

Patch release: documents that MCP servers offering an X-API-KEY header in addition to OAuth Bearer (e.g. Gamma's official MCP) can be federated through the hub today using the existing per-server headers config — no new hub code needed.

Wire gamma into the hub

```bash

In ~/.slm-mcp-hub/config.json:

"gamma": {
"enabled": true,
"type": "http",
"url": "https://mcp.gamma.app/mcp",
"headers": {"X-API-KEY": "<your-key-from-gamma.app-dashboard>"}
}

Then hot-add via v0.2.0 lifecycle (no hub restart):

slm-hub server reload
```

Fixed

• Minor: cosmetic cleanups in connection error messages.

Coming in v0.3.0

Full OAuth-DCR federation (RFC 9728 protected-resource metadata, RFC 7591 dynamic client registration, OAuth 2.1 PKCE flow with loopback callback) for MCPs that only support OAuth Bearer with no API-key bypass.

654 tests pass. Backward compatible.