Full-width muted band; RANGE renders a span pill (1914–1918) with a Zeitraum
aria-label (REQ-009); a RANGE with no end degrades to the start year, no pill,
no crash (REQ-010). World glyph is a redundant non-color cue with sr-only label
(REQ-018); text uses text-ink-2 to hold AA in both themes (REQ-019).
Refs #779
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
