feat(studio): gesture-to-keyframes recording

[miguel-heygen]

Summary

• Gesture recording mode: select element, press Record (or R key), drag in preview while timeline plays — mouse/scroll gestures are sampled at ~60fps and converted to editable GSAP keyframes
• Multi-property recording via modifier keys: plain drag (x/y), scroll (z), Shift+drag (rotationX/Y), Alt+drag (rotation), Cmd+drag (opacity), Cmd+scroll (scale)
• Ramer-Douglas-Peucker simplification reduces 180+ raw samples to 5-15 clean keyframes
• Velocity-to-ease inference auto-matches gesture acceleration curves to GSAP ease presets
• Ghost trail SVG overlay visualizes the motion path during and after recording
• Post-record preview panel with tolerance slider, property/ease display, commit/discard/re-record

Test plan

• Select an element, press R or click Record button
• Drag in preview while timeline plays — verify trail overlay appears
• Stop recording — verify preview panel shows with keyframe count
• Adjust smoothing slider — verify keyframe count updates
• Commit — verify GSAP keyframes written to code tab
• Re-record — verify previous take is replaced
• Test modifier keys: Shift+drag, Alt+drag, Cmd+drag, scroll

[miguel-heygen]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• feat(studio): gesture-to-keyframes recording #1256 👈 (View in Graphite)
• feat(studio): MotionPathPlugin arc motion + design panel redesign #1232
• fix(studio): keyframe stability + modular border-radius editor #1217
• main

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