textInputFade becomes colorFade in theme.go and serves AvatarGroup,
Image retry, Tag and EditableText, which used internal.Fade. MyGo already
skips element transitions under ReduceMotion, so dropping the Motion
check keeps behaviour.
RuleDiamond draws the rule-diamond-rule of Heading, Dialog, Result, Card
titles and the ornament Divider; Frame draws the inset line with corner
diamonds of Card and decorated Dialog. Both snap the diamonds, and the
rule's diamond sits on the pixel-aligned line.
Snapshots: card (all densities, light and dark) moves the title rule's
diamond onto the rule's pixel row, an 8x8 region. Decorated dialog
(both densities, light and dark) loses the surface-colored halo under
each corner diamond, so the frame line now runs into the diamond as on
Card and the panel border is no longer notched at the corners.
Heading, Divider and Result render unchanged.
ZacharyZhang-NY