[AsPulse]

VectorLayer, Frame, Flex, and Padding never overrode VectorComponent::paint_bounds, so they reported only their own (0,0)..size layout box while their render returned that same rectangle as view_box. The contract #84 enforces — view_box == paint_bounds — therefore held even though the bounds silently dropped whatever a child painted outside the box, and rasterization clipped it. The raster variants of all four have unioned their children's paint bounds into their own since #7; on the vector side only Fragment was corrected in #84.

Change

• Override paint_bounds on the vector VectorLayer, Frame, Flex, and Padding to start from (0,0)..size and union in every child's paint bounds, and return that same rectangle as render().view_box.
• Add a container paint-bounds contract test asserting that each container reports the same bounds in both worlds, which catches bounds that drop child overflow — something the view_box == paint_bounds enforcement cannot see — and records DecoratedBox and Clip as the containers that pin their bounds on purpose.
• Add a CPU rasterization regression for children spilling off both corners of a VectorLayer, covering the negative view-box origin.
• Correct the English and Japanese layout tutorials, which described paint_bounds as a raster-side responsibility.
• Add a major changeset because corrected bounds can change existing rendered video pixels.