## What changed
- Upgrade `rmcp` and `rmcp-macros` from 3.1.2 to 3.1.3.
- Preserve authentication-required and retryable transport classifications when modern MCP discovery falls back to legacy initialization.
- Prevent unrelated discovery errors from triggering legacy fallback while retaining their diagnostics.
## Testing
- Cover authentication challenges and transient initialization failures during legacy fallback.
- Verify that a failed OAuth issuer check does not consume the pending authorization state.
GitOrigin-RevId: 957c0873fec1148883dd163fbaeb77d7593d8c53