chore: remove college basketball (CBB) from iOS app

Remove CBB (~5,000+ games per season) to reduce complexity.

Changes:
- Remove .cbb enum case from Sport
- Remove CBB theme color (cbbMint)
- Update documentation to reflect 7 supported leagues

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

SportsTime/Core/Theme/ViewModifiers.swift

@@ -217,7 +217,6 @@ extension Sport {
         case .mls: return Theme.mlsGreen
         case .wnba: return Theme.wnbaPurple
         case .nwsl: return Theme.nwslTeal
-        case .cbb: return Theme.cbbMint
         }
     }
 }