feat(app): add file and folder path context actions to desktop app

[olibols]

Issue for this PR

Closes #14784
Closes #11820
Closes #11620

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

Adds desktop-focused context menu actions for session files/folders:

• Copy relative path
• Copy absolute path
• Copy file contents (files)
• Reveal in file explorer (desktop/local)
• Open in default app (desktop/local)

This improves desktop workflow by making common file actions available directly from the UI context menus.

How did you verify your code works?

• Ran bun run typecheck in packages/app
• Pre-push checks ran bun turbo typecheck successfully
• Manually tested context menu actions in desktop/local flow

Screenshots / recordings

8AH2a3QKsv.mp4

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

If you do not follow this template your PR will be automatically rejected.

[github-actions]

Thanks for your contribution!

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Please:

1. Open an issue describing the bug/feature (if one doesn't exist)
2. Add Fixes #<number> or Closes #<number> to this PR description

See CONTRIBUTING.md for details.

[github-actions]

Thanks for updating your PR! It now meets our contributing guidelines. 👍