fix(engine): sample-accurate volume automation so dense fades keep their audio #6464

Job	Run time
Detect changes	14s
Preflight (lint + format)	37s
regression-shards (shard-4, style-16-prod style-9-prod style-17-prod iframe-render-compat variabl...	20m 27s
regression-shards (shard-2, style-15-prod hdr-hlg-regression style-1-prod many-cuts vfr-screen-re...	22m 44s
regression-shards (shard-6, overlay-montage-prod style-12-prod chat missing-host-comp-id png-sequ...	18m 1s
regression-shards (shard-7, sub-composition-video style-18-prod raf-ball-render-compat font-varia...	21m 13s
regression-shards (shard-5, style-4-prod style-11-prod style-2-prod animejs-adapter typegpu-adapt...	19m 17s
regression-shards (shard-8, style-13-prod style-6-prod vignelli-stacking gsap-letters-render-compat)	17m 58s
regression-shards (shard-3, style-7-prod style-8-prod style-10-prod css-spinner-render-compat web...	17m 56s
regression-shards (shard-1, hdr-regression style-5-prod style-3-prod mov-prores)	18m 40s
regression	4s
	2h 37m 11s

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