Video panel: user control of position, scale, and overlay visibility

[veillette]

Goal

Give users direct control over where the video appears on screen, how big it is, and whether measurement overlays are visible — without breaking alignment between the video and overlay tools (coordinate system, calibration, measuring tape, angle tool).

Desired behavior

• Reposition the video panel (and all attached overlays) by dragging
• Scale the video display (e.g. 50%–200%) with a resize control, anchored so overlays stay geometrically aligned with the video
• Toggle overlay visibility (show/hide measurement tools) with a single control
• Overlay drag/keyboard interaction should account for the current offset and scale

Context

An exploratory local branch (videoScaling, Feb 2026) prototyped this with:

• A VideoControlFrameNode — semi-transparent header with drag handle, eye toggle, and scale label
• Model properties: videoOffsetProperty, videoDisplayScaleProperty, videoOverlaysVisibleProperty
• Updated overlay nodes to convert between video-local and screen coordinates using offset + scale

That branch was never merged. The sim has since been reorganized (screen-name/ → track-lab/), and current main has related panel/header/scaling work (panelSizeScaleProperty, panelHeaderBar, etc.). This issue captures the user-facing intent so it can be implemented cleanly against the current codebase rather than reviving the old branch.

Acceptance criteria (draft)

• User can move the video panel; overlays move with it
• User can scale the video within a sensible range; overlays remain aligned (fixed anchor point)
• User can hide/show overlays without affecting video playback
• Coordinate tools remain accurate at all scale/offset settings
• npm run lint && npm run check && npm run build pass