Static placeholder shapes used in place of CircularProgressIndicator for
async-loading sections. No animation — the design system rule is that
non-functional motion is forbidden (StreakSparkline's placeholder bars
follow the same rule). The shapes mirror the eventual content's geometry
so there's no layout shift when real data arrives.
Bordered card placeholder — matches the geometry of ActiveGoalCard,
DueTodayCard, and DomainStatTile so swapping in real content doesn't
jolt the layout. Adapts inner content to short vs tall cards so the
placeholder lines never overflow the bordered box.