feat: monochrome black & white rebrand + new Pudu robots

- Convert site from royal-blue theme to black/white monochrome (desaturate
  all blue-hued colors; keep WhatsApp green and error red)
- Swap blue circular brand logo for mono YS mark; regenerate favicon/PWA icons
- Add 6 Pudu robots (CC1 Pro, MT1 Max, MT1 Vac, T600, T600 Underride, BG1 Pro)
- Fix favicon.ico to RGBA (Next 16 Turbopack decode) and Stripe apiVersion type

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

src/components/ui/CursorSpotlight.tsx

@@ -8,7 +8,7 @@ type Props = {
   className?: string;
 };
 
-export function CursorSpotlight({ color = 'rgba(39, 63, 148, 0.18)', size = 520, className = '' }: Props) {
+export function CursorSpotlight({ color = 'rgba(94, 94, 94, 0.18)', size = 520, className = '' }: Props) {
   const ref = useRef<HTMLDivElement | null>(null);
   const [pos, setPos] = useState<{ x: number; y: number } | null>(null);
   const [enabled, setEnabled] = useState(false);