Introduce per-server `forward_inbound_auth` flag that controls whether the
inbound MCP bearer token is propagated to outbound MCP transport calls.
Implemented as a fast-agent monkey-patch auto-installed on package import,
preventing accidental credential leakage to unrelated downstream servers.
Update docs to describe the two bearer token consumers (LLM provider
passthrough and opt-in downstream MCP forwarding) with a config example.
Robert Helewka
be71709608