## Why
Consumer analytics lacked a per-chat view of allowance usage and balance credit debits.
## What changed
- Add a Top chats panel for up to 100 local chats active in the past 30 days, including discovered descendants and excluding archived roots.
- Show weekly and five-hour usage as percentages of current full limits, plus balance credits including adjustments. Preserve exact credit decimals and distinguish missing values from zero.
- Support cycling sort metrics with `s`, a top-five dashboard summary, and expandable model, reasoning effort, and speed breakdowns.
- Query task usage through `query_v2` with bounded, disjoint descendant groups. Retain partial and unavailable rows, hide titles when usage is unavailable, and report ranking coverage and freshness.
## Testing
Add backend and TUI tests covering decimal precision, request and response validation, paginated archived descendants, unavailable responses, metric selection, title hiding, and top-five rendering.
GitOrigin-RevId: b8f233166576389c8212bb97eceb7c6be7f5f51d
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