fix(usage-tracker): support current provider keys and all windows

[MateoCerquetella]

Summary

• map current BB wire keys (claude-code, acp-cursor) to stable Usage Tracker provider IDs while retaining legacy aliases
• isolate missing providers instead of failing the whole usage snapshot
• render and retain every additional usage window after the canonical five-hour and weekly rows
• keep the expanded card responsive and keyboard-accessible with focus restoration, scoped Escape handling, and scroll-safe overflow

Verification

• npm run check
• 23 focused Usage Tracker tests
• live BB 0.40 expanded, compact, overflow, focus, ARIA, refresh, and Escape verification
• three independent final review passes: PASS
• Empirical completion level: integrated

Closes #13
Closes #19