Prevent initial autoplay when disabled

[KaannKara]

Summary

• install an early page-world play guard before YouTube can start the first watch-page playback
• mirror the autoplay-disable setting into page localStorage for the early guard
• add Jest coverage for blocked and allowed initial play calls

Fixes #1461

Testing

• npm ci --silent
• npm test -- --runInBand --json --outputFile=/tmp/youtube-jest-full2.json
• git diff --check

[ImprovedTube2]

hi and thank you @KaannKara
LLM issues.
Our timing is worth analyzing and tuning if you will.