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/InteractiveHotspot.tsx

@@ -75,8 +75,8 @@ export function InteractiveHotspot({
       >
         <sphereGeometry args={[0.025, 16, 16]} />
         <meshStandardMaterial
-          color={hovered ? '#3b82f6' : '#f59e0b'}
-          emissive={hovered ? '#3b82f6' : '#f59e0b'}
+          color={hovered ? '#999999' : '#f59e0b'}
+          emissive={hovered ? '#999999' : '#f59e0b'}
           emissiveIntensity={hovered ? 0.8 : 0.4}
           transparent
           opacity={0.9}
@@ -110,13 +110,13 @@ export function InteractiveHotspot({
             style={{
               background: 'rgba(255, 255, 255, 0.95)',
               backdropFilter: 'blur(8px)',
-              border: '1px solid rgba(59, 130, 246, 0.3)',
+              border: '1px solid rgba(153, 153, 153, 0.3)',
               borderRadius: '8px',
               padding: '8px 12px',
               whiteSpace: 'nowrap',
               fontFamily: 'system-ui, -apple-system, sans-serif',
               fontSize: '12px',
-              color: '#0a0a0c',
+              color: '#0b0b0b',
               boxShadow: '0 4px 12px rgba(0, 0, 0, 0.3)',
               animation: 'fadeIn 0.15s ease-out',
             }}
@@ -125,7 +125,7 @@ export function InteractiveHotspot({
             <div
               style={{
                 fontSize: '10px',
-                color: '#8891C7',
+                color: '#a8a8a8',
                 display: 'flex',
                 alignItems: 'center',
                 gap: 4,
@@ -133,7 +133,7 @@ export function InteractiveHotspot({
             >
               <span
                 style={{
-                  background: '#3b82f6',
+                  background: '#999999',
                   color: 'white',
                   padding: '2px 6px',
                   borderRadius: '4px',