feat: add session archive/unarchive support to TUI

[uriva]

Issue for this PR

Closes #13964

Type of change

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

What does this PR do?

The backend already supports archiving sessions but the TUI had no way to use it. This adds:

• /archive slash command and session_archive keybind to archive the current session
• Archive/unarchive actions in the session list dialog, with tab to toggle between active and archived sessions
• Auto-navigate home when current session is archived
• Selecting an archived session unarchives it

4 files changed: config.ts (keybind), dialog-session-list.tsx (archive toggle + keybinds), routes/session/index.tsx (/archive command), app.tsx (navigate home on archive event).

Related: #12020 (desktop archive was disabled due to no restore path)

How did you verify your code works?

Typecheck passes. Manually tested archive/unarchive via slash command, keybind, and session list dialog. Verified archived sessions don't appear in default list, appear under "Archived Sessions" tab, and unarchive correctly.

Screenshots / recordings

N/A — no visual layout changes, only new keybind actions and list filtering.

Checklist

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

[github-actions]

Thanks for your contribution!

This PR doesn't have a linked issue. All PRs must reference an existing issue.

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]

The following comment was made by an LLM, it may be inaccurate:

[uriva]

The two CI failures are unrelated to this PR:

• e2e (windows): Flaky Playwright test — "can send a prompt and receive a reply" timed out waiting for a response (80 passed, 2 failed, 2 skipped). This is a prompt/session e2e test, not related to archive changes.
• test (linux): Gate job that fails because e2e (windows) failed. Cascading failure.

All checks relevant to this PR pass: typecheck, unit (linux), e2e (linux), check-standards.

[uriva]

Friendly ping @thdxr @adamdotdevin — rebased onto latest dev, CI passing. Ready for review whenever you have a moment!

[B67687]

This would be very helpful for my workflow. Let me know when it's rebased and I can test it.

[B67687]

I rebased this onto current dev and created a new PR: #22328

The original had conflicts since dev moved forward after March. This version resolves them properly.

Thought you might want to merge from this or just reference it. Happy to close if you're re-merging it yourself.