fix(skills): pass rational fps to capture helpers

[miguel-heygen]

Summary

• pass Producer capture helpers the rational FPS shape required by the current engine contract
• cover both animation-map and contrast-report with a regression test using a stub Producer package

Reproduction

animation-map.mjs --fps 30 passed fps: 30, making beginFrameIntervalMs become NaN; Linux capture then failed with HeadlessExperimental.beginFrame: Invalid parameters ... frameTimeTicks ... double value expected.

Verification

• bun run test:skills (231 tests passed)
• bun run lint:skills
• targeted oxfmt check
• real animation-map run against @hyperframes/producer@0.7.56 and Chrome 150 completed without PUPPETEER_EXECUTABLE_PATH

Severity: P2
Feedback: Slack 1783939612.421019

[miguel-heygen]

Consolidated into #2409, which preserves this change alongside the compatible animation-map capture fix and its regression coverage.

[miguel-heygen]

Closing in favor of #2409.