feat: add copy last transcript tray action

[anntnzrb]

Before Submitting This PR

• I have searched existing issues and PRs (open + closed)
• I have read CONTRIBUTING.md

Human Written Description

Related Issues/Discussions

Fixes #
Discussion: #597

Community Feedback

Discussion: #597

Testing

• bun run format:check
• bun run lint
• bun run build
• cd src-tauri && cargo test

Screenshots/Videos (if applicable)

N/A

AI Assistance

• No AI was used in this PR
• AI was used (please describe below)

If AI was used:

• Tools used: Codex CLI (OpenAI)
• How extensively: scaffolding + edits + test running

[cjpais]

Thanks I don't see why not to add this. I've run into it a few times and it's minimally invasive. When I get a chance I'll review the code and pull in