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/app/layout.tsx

@@ -45,7 +45,7 @@ export const metadata: Metadata = {
 export const viewport: Viewport = {
   width: 'device-width',
   initialScale: 1,
-  themeColor: '#0a0a0c',
+  themeColor: '#0b0b0b',
 };
 
 export default function RootLayout({