Add a Last 60 days option to the usage time-range select

[rjimeno-mz]

Summary

• Adds 60: "Last 60 days" to timeRangeOptions in TimeRangeSelect.tsx, giving a mid-range window between the existing 30- and 90-day options.
• No other changes needed: timeRange flows through as a plain number to getDayAlignedRange/useDailyCostsBreakdown with no per-value special-casing, so the new option works structurally like the rest.

Test plan

• yarn typecheck
• yarn lint
• New TimeRangeSelect.test.tsx: dropdown lists Last 60 days between Last 30 days and Last 90 days; selecting it calls setTimeRange(60)
• Full src/platform/billing suite passes (37 tests)

Resolves SAS-170.

[linear-code]

SAS-170