feat(app): add confirmation dialog before archiving session

[herjarsa]

Feature request

Show a confirmation dialog before archiving a session from the message timeline, following the same pattern as the existing DialogDeleteSession, so accidental archive clicks are prevented.

Expected behavior

Clicking archive on a session shows a confirmation dialog with the session name before archiving.

[github-actions]

This issue doesn't fully meet our contributing guidelines.

What needs to be fixed:

• Feature request issues should have a title starting with [FEATURE]: (e.g. [FEATURE]: Add confirmation dialog before archiving session)
• The feature request template requires a verification checkbox confirming the feature hasn't been suggested before

Please edit this issue to address the above within 2 hours, or it will be automatically closed.

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This issue might be a duplicate of existing issues. Please check:

• [FEATURE]: Add unarchive/restore for archived sessions and confirmation dialog #32355: Explicitly requests a confirmation dialog before archiving, plus unarchive/restore functionality
• [FEATURE]: Accidentally archiving a session hides it permanently with no UI to restore it. #32594: About accidentally archiving sessions with no restore — related context

If you believe this was flagged incorrectly, please let a maintainer know.

[github-actions]

This issue has been automatically closed because it was not updated to meet our contributing guidelines within the 2-hour window.

Feel free to open a new issue that follows our issue templates.