refactor(animations): converge P1 motion durations to ≤300ms target

- 151 scripted + 1 manual duration fixes across 46 files
- framer entrance 0.5/0.6s -> 0.3s
- Tailwind hover -> duration-150, entrance -> duration-300
- preserve flip-clock/page-transition per semantic decision
- design-system.ts dead-code deferred
- P1 violations 156 -> 5; P0 remains 0; OK class 249 -> 400
- verified: tsc clean, eslint 0 errors
- verified: 130/130 jest suites, 1573 passed
- verified: visual regression 46/46 zero-pixel diff

Co-Authored-By: 阿睿 <workbuddy@tencent.com>

src/components/ui/brand-visuals.tsx

@@ -92,7 +92,7 @@ export function BrandStamp({ children }: { children: React.ReactNode }) {
       initial={shouldReduceMotion ? {} : { scale: 1.3, opacity: 0, rotate: -12 }}
       whileInView={{ scale: 1, opacity: 1, rotate: -5 }}
       viewport={{ once: true }}
-      transition={{ duration: 0.5, ease: [0.16, 1, 0.3, 1] }}
+      transition={{ duration: 0.3, ease: [0.16, 1, 0.3, 1] }}
       className="inline-block px-3 py-1.5 border-2 border-[var(--color-brand)] rounded-sm"
       style={{
         transform: 'rotate(-5deg)',

src/components/ui/stats-showcase.tsx

@@ -72,7 +72,7 @@ export function StatsShowcase({
         <div
           key={i}
           className={cn(
-            'relative p-8 sm:p-10 md:p-12 text-center transition-all duration-500 group',
+            'relative p-8 sm:p-10 md:p-12 text-center transition-all duration-300 group',
             isDark ? 'bg-dark-bg hover:bg-dark-bg-secondary' : 'bg-bg-primary hover:bg-bg-hover'
           )}
         >
@@ -131,7 +131,7 @@ export function StatsShowcase({
 
           {item.accent && (
             <div
-              className="absolute top-0 left-1/2 -translate-x-1/2 w-12 h-0.5 opacity-0 group-hover:opacity-100 transition-opacity duration-500"
+              className="absolute top-0 left-1/2 -translate-x-1/2 w-12 h-0.5 opacity-0 group-hover:opacity-100 transition-opacity duration-150"
               style={{ backgroundColor: item.accent }}
             />
           )}