fix: elevate track-container z-index when likers tooltip is open (#485)
the previous fix only elevated the .likes element, but z-index on a child
doesn't help when sibling track-containers are in the same stacking context.
now:
- .track-container.likers-tooltip-open gets z-index: 60 (above header at 50)
- removes the ineffective .likes.tooltip-open z-index
- the entire track elevates above siblings, ensuring the tooltip renders on top
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Co-authored-by: Claude <noreply@anthropic.com>
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