- Add DESIGN.md: full visual design reference covering colours, typography,
  spacing, all UI elements, animations, and screen layout
- Start duck in Queens Road (room 6, top-right) instead of Attara Kacheri
- Increase room/park label opacity 0.38 → 0.75 for readability
- Move top label y=7 → y=13 and bottom label y=GH-3 → y=GH-10 to
  clear the north and south exit arrows

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>