Improve SSH keypair UX consistency — items 4 & 5 from SSH keypair UX proposal

## Objective

Implement items 4 and 5 from Jihyun Kang's SSH keypair UX improvement proposal (Loop document: "SSH 키페어 UX 일관성 개선").

## Context

- SSH keypair management components exist: `SSHKeypairManagementPanel`, `KeypairInfoModal`, etc.
- PR #6019 contains related SSH keypair management discussion
- The exact specifications for items 4 and 5 are in the Loop document linked from the Teams thread

## Prerequisites

- Review the Loop document for exact requirements of items 4 & 5
- Check Teams thread for additional context and decisions

## Related Files

- SSH keypair management components in `react/src/components/`
- User Settings SSH-related UI

## Effort & Risk

- **Effort**: Medium (UX consistency changes)
- **Risk**: Low (UX improvements, no core logic changes)

## References

- Teams discussion: UX Consistency improvements for SSH keypairs
- Loop doc: SSH 키페어 UX 일관성 개선
- PR #6019: SSH keypair management spec discussion

JIRA Issue: FR-2375