v0.177.0: Open artifacts in your default app, plus mission, transcript, and app UI fixes

New features

- Open artifacts externally - Artifact preview cards can now open in your default app (app)

Improvements

- Code block font - Code blocks now render in Geist Mono for clearer monospaced text (app)
- Attachment-only messages - You can now send chat messages that contain only attachments (app)

Bug fixes

- Approval details toggle - Option+E dead-key accents no longer interfere with toggling approval details
- Transcript repaint - The transcript now repaints correctly after viewing plan details
- Computer removal - Removing a computer no longer shows a spurious session-archiving warning
- Mission interrupts - Missions now pause correctly when the orchestrator is interrupted
- Agent browser cleanup - Orphaned browser automation processes are now cleaned up reliably
- Unavailable sessions - Sessions that can't be loaded now show a clear unavailable state (app)
- Skill colors - Loaded skills now display with the correct colors (app)