Expose mergeable camera-shake rate bins for p99

[kstonekuan]

Camera-shake summaries currently discard assessed frame-pair rates after computing mean, RMS, and maximum. That prevents consumers from calculating a run-wide p99 across windows without decoding media again.

This adds assessed-duration rate bins to the existing one-pass summary and a duration-weighted percentile helper. Bins are one degree per second below 4,096°/s and 64 per doubling above it, keeping memory bounded. The helper returns the selected bin's upper bound, capped by the observed maximum. Compensated per-bin accumulation and precise prefix sums keep 30 fps percentile boundaries stable without treating a genuinely below-threshold bin as complete. Existing mean, RMS, maximum, and coverage calculations are unchanged.

Validation: Ruff, ty, 2,385 tests passed (8 skipped), including exact-boundary and below-threshold regressions.

[greptile-apps]

Confidence Score: 5/5

[Medium risk] Adds camera shake rate binning and percentile calculation.

The PR appears safe to merge based on the changes since the previous review.

Summary

The PR adds mergeable, duration-weighted camera-shake rate bins and a percentile helper, with documentation and tests. Since the previous review, it removes the near-boundary isclose shortcut and revises the boundary test.

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