### Vector graphics (Draft): a title card and credit roll in the corpus

`wai/vector-conformance/` gains `motion/stroke-titles`: a 1280 × 720 document at 25 fps
in the default stroke set, a lower third that slides in, holds and fades as a group, and
a credit roll that rises three design pixels a frame. Each line's window is cut to the
frames at which it meets the canvas (graphics-vector §5.4, *Where a block is*). Every
frame's digest is in its expected file, so the native, WASI, Node and three-engine
browser legs and the independent checker each check all of them.

