Fix GamePlaying detection during Fever

[vanisoul]

Fixes #617

Fever can shift the sampled color at the regular GamePlaying (916,318) probe to a difference of exactly 80. Because page detection uses strict diff < threshold, the existing threshold of 80 rejects that frame.

This changes only the affected probe threshold from 80 to 90, avoiding broader page-recognition changes. The committed index.zip release artifact was rebuilt from the updated source.

驗證：

• npm run build succeeded in scripts/com.r2studio.TsumBeta
• confirmed the rebuilt archive contains the threshold of 90
• git diff --check passed

Runtime verification in Redroid x86_64 with TsumBeta remains necessary to confirm uninterrupted Fever gameplay after deployment.