Controlled, externally-anchored Coachmark (ref/selector/DOMRect) reusing
Popover-style portal positioning, plus OnboardingSpotlight (dimmed cut-out +
stepped bubble). Both compose existing atoms only. Also fixes the @almadar/std
stdTimer drift in avl-story-schemas that broke the build (stdTimer→stdList).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>