- Animate usage bar fills (compact meters, overview rows, provider
  rows, credits, provider cost, cost history) and tab/hover color
  transitions.
- Tab bar: breathable spacing, keep the provider meter visible on the
  selected tab, add scroll edge fades to the tab strip, and drop the
  dead Overview tab meter block plus the now-unused overviewPercent().
- Micro-interactions: pointing-hand cursor on clickable areas and a
  spinning refresh icon in the compact representation while loading.
- Refresh README screenshots with the updated UI.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>