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/page.tsx

@@ -160,7 +160,7 @@ function SectionHeading({ eyebrow, title, description }: { eyebrow: string; titl
         <span className="text-gradient" style={{ fontWeight: 500 }}>{title}</span>
       </h2>
       {description && (
-        <p style={{ margin: 0, color: '#DEE0F0', fontSize: 'clamp(0.95rem, 2vw, 1.05rem)', lineHeight: 1.7 }}>
+        <p style={{ margin: 0, color: '#e7e7e7', fontSize: 'clamp(0.95rem, 2vw, 1.05rem)', lineHeight: 1.7 }}>
           {description}
         </p>
       )}