[Gap]: Document Bearer Token auth for remote MCP servers

[danbarr]

Gap

The remote-MCP auth dropdown exposes four options: Auto-Discovered, Bearer Token, OIDC, OAuth2. run-mcp-servers.mdx lines 137-180 document only three (missing Bearer Token). Companion to #456.

Source in app (v0.30.0)

• renderer/src/features/mcp-servers/components/remote-mcp/form-fields-auth.tsx — AUTH_FIELD_MATRIX with bearer_token entry

Docs to update

• docs/toolhive/guides-ui/run-mcp-servers.mdx (remote MCP auth section)

Introducing PR

stacklok/toolhive-studio#1455 — feat(remote-mcp): support bearer token authentication

Parent

Part of #751.