v0.56.1

Fixed

• Sketch strokes and pins no longer see the hidden main scene while a
  prefab is open. In Prefab Mode the depth contour traced the room
  behind the prefab, and a pin or a surface stroke could land on it:
  the renderer scan returned the main scene's objects even though the
  stage does not draw them. Picking and the contour now keep only what
  the current stage contains. Design note
  docs/design-notes/2026-09-17-scene-sketch-strokes.md section 9.
• The wheel now moves an axis-locked sketch plane from any viewpoint.
  A Z plane seen from above did not respond, because the depth step fell
  back to the view direction when it was nearly perpendicular to the
  plane; an axis plane now always moves along its own normal. Same note.
• The sketch plane's readout (depth, axis, key hints) sits at the Scene
  view's top-left instead of next to the cursor, so it is visible for
  every plane and view. Same note.