TUI: add per-profile backup history view

[rmanibus]

Summary

Backup history is most useful in the context of a selected profile.

We should add a profile-scoped backup history view in the TUI so operators can inspect recent snapshots for the selected profile without leaving the dashboard.

Scope

• Add a backup history subview for the selected profile
• Show recent snapshots associated with that profile
• Include useful metadata such as snapshot time and reference
• Keep the initial slice read-only
• Integrate cleanly with the existing profile selection flow

Why

• Backup history is more actionable when tied to a profile than a store
• It builds naturally on the current dashboard and selected profile pane
• It creates a path toward future restore/browse actions

Related: #132, #211, #213, #218