The Overview tab was a 150-line inline copy of GlobalTab, which the Usage &
Spend and Sessions tabs already use: the same surface states, focus ring,
keyboard navigation, strip reveal, selection report, tooltip and icon-only
layout. It now instantiates GlobalTab, and the surface checks that pinned the
inline copy's ids assert the GlobalTab wiring instead.

No visible or behavioral change; no changelog entry.

Co-authored-by: Simone <185146821+Lucenx9@users.noreply.github.com>
Co-authored-by: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Co-authored-by: Grok Bot <grok-bot@users.noreply.github.com>