Optimize create.js Ticker with idle throttling and tab visibility handling

[stutijain2006]

This PR introduces performance optimizations to reduce unnecessary CPU usage when Music Blocks is idle or running in the background.

Previously-

1. create.js ticker continued running at 60 FPS even when the user was inactive
2. Rendered continued even when the tab was hidden
3. This causes unnecessary main thread workload and CPU usage.

After this PR-

1. Removes redundant ticker initialization from index.html
2. Implemented controlled idle throttling by-

• Active = 60 FPS
• Idle (after 5 second inactivity) = 1 FPS

3. Adds visibilitychange listener which -

• Pauses ticker when tab is hidden
• Resumes correctly when the tab becomes visible.

4. Restores active FPS immediately when the interaction resumes.

Runtime Impact-
Before: Main Runtime thread : 8469 ms

After : Main Runtime thread : 7371 ms

That is a reduction of 1100 ms in main runtime workload during a 30 sec interaction session.

This is a runtime efficiency optimization- not a lighthouse score improvements leading to -

• Reduced CPU usage
• Lower battery consumption

[github-actions]

✅ All Jest tests passed! This PR is ready to merge.

[github-actions]

✅ All Jest tests passed! This PR is ready to merge.

[kartikktripathi]

The idle throttling and visibility handling work correctly in testing.
Verified:

• No first interaction delay after idle
• Playback timing remains stable
• Background tab pause/resume works without tempo jumps
• Rapid tab switching does not create duplicate playback
• Ticker framerate restores correctly (60 → idle → 60)
• npm run test was run, and passed all the tests

The optimisation reduces unnecessary runtime work and behaves safely.

One small note: the recursive setTimeout idle check isn’t cleaned up if Activity is reinitialised, which could potentially create multiple loops in future refactors. Not blocking for this PR.

LGTM, Thanks for the contribution!

[kartikktripathi]

@walterbender, I believe this PR is ready to be merged.
Thanks!

[walterbender]

Can you either rebase or run prettier on activity.js?

[stutijain2006]

Can you either rebase or run prettier on activity.js?

Done

[github-actions]

✅ All Jest tests passed! This PR is ready to merge.