Phase 7.1: add 30+ missing i18n keys for queue timeout, game states,
achievements, and chat. Replace hardcoded Arabic in chess game scene
with t() calls.

Phase 7.3: replace hardcoded hex colors in chess HUD and draw dialog
with CSS variables (--text-primary, --bg-surface, --success, --error).
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>