fix: Audio sometimes not added to exports

[StickmanRed]

Description

Several projects were reported to be missing certain audios in their .mp4 exports. The bug: a RangeError, originating in Wick.AudioTrack. Further investigation uncovered a discrepancy in the two audio buffers' sizes: the output delayedBuffer contained one less element than originalBuffer, causing Float32Array.set to panic and fail to return the audio data.

The length of an AudioBuffer equals its sampleRate times its duration. AudioTrack.addStartDelayToAudioBuffer uses this to calculate the length of the output buffer:

let lengthOfDelay = ctx.sampleRate * delaySeconds;
let lengthOfOriginalSound = ctx.sampleRate * originalBuffer.duration;

Under certain circumstances, however, the result of these multiplications is subjected to a floating-point error, returning such products as 199998.99999999997 instead of 199999. As AudioContext.createBuffer requires an integer length, it discards the decimal part of this result, thus causing the RangeError and the audio's disappearance.

This PR rounds the length to the nearest integer, eliminating the miscalculation and, hopefully, solving the last audio mystery once and for all.

Testing

1. Load one of the affected projects.
2. Export either a .mp4 video or a .wav audio.
3. The audio should play in the export as expected.

Checklist

• This PR does not make sense to split into smaller PRs.