* feat(skills): motion-blur-streak — per-frame-driven form for elements riding a baked track
Extends rules/motion-blur-streak.md with a Per-Frame-Driven Carve-In: when an element is driven
from a baked track (tracked insert, shake-matched title) there is no tween window to share, so the
envelope becomes a per-frame function of the track delta — velocity-gated text-free silhouette
ghosts (Path B, the default for driven subtrees) or a rotate/blur/counter-rotate filter sandwich
(Path A), streak axis from atan2 of the delta. Adds the Values rows, the constraint, and updates
the rules-index row.
* fix(skills): keep motion-blur-streak trail opacity independent of seek order
The driven ghost trail read the lead opacity written by another tween, so a frame could get a different trail opacity depending on the previous seek. Ghosts now sit inside the positioned, faded track wrapper and take the fade as group opacity. The snippet also names which element owns position, rotation and counter-rotation so the transform writes cannot clobber each other.
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Co-authored-by: Miguel Ángel <miguel.sierra@heygen.com>