In the terminal, an admin marks several repositories and archives them in one keypress, and u undoes it #2520

Replaces #2519, terminal only. The home's checkboxes are #2512. Starts after #2511 (pull #2517) puts the archive verb in src/fleet/verbs.ts.

Done looks like:

• [ ] On the terminal's home list of repositories, space marks a row and a archives the marked ones through the fleet archive operation (applyFleetIds in src/actions/fleet.ts), after a one-line preview that names them. A toast says 'archived N — u undoes it'.
• [ ] u calls undoFleetOp, as src/tui/screens/limbs.ts does, and the repositories come back.
• [ ] Bindings are disabled for a non-admin. No new action code: the terminal calls what the API calls.
• [ ] Test in test/tui-screens.test.ts (or a new test/tui-archive.test.ts): mark two, archive, both archived; undo, both awake; a non-admin's a does nothing.

Files: the terminal home screen in src/tui/screens/, the test. Do not touch src/web.