perf(motion): 第二批入场动效时长收敛至 300ms（4 文件 21 处）

承接 8fb5aae，继续清理 Task #16 的 P0 硬违规（>700ms 明确禁止）：

- contact-content-v3 (7) / case-detail-page (6) / product-detail-content-v3 (5) /
  detail-hero (3 处入场)
- 审计：P0 54 → 33，P1 163 持平，P2 28 持平
- 只改 duration，保留原 delay（与首批先例一致）；改动行已逐行核验为纯动效行

验证：
- tsc --noEmit 0 error；eslint 4 个改动文件 0 error
- 单测 131 套件 / 1662 通过 / 2 跳过 / EXIT=0（与基线一致）
- 视觉基线零变动：reducedMotion+animations disabled 下终态一致，
  时长改动不改变最终像素；不带 -u 复跑 92 用例 EXIT=0

src/components/detail/detail-hero.tsx

@@ -101,7 +101,7 @@ export function DetailHero({
                 y: 0,
                 filter: 'blur(0px)',
                 transition: {
-                  duration: 0.9,
+                  duration: 0.3,
                   ease: [0.22, 1, 0.36, 1] as const,
                 },
               },
@@ -120,7 +120,7 @@ export function DetailHero({
                 opacity: 1,
                 y: 0,
                 transition: {
-                  duration: 0.75,
+                  duration: 0.3,
                   delay: 0.25,
                   ease: [0.22, 1, 0.36, 1] as const,
                 },
@@ -189,7 +189,7 @@ export function DetailHero({
         <motion.div
           initial={{ opacity: 0 }}
           animate={{ opacity: 1 }}
-          transition={{ delay: 1.5, duration: 0.8 }}
+          transition={{ delay: 1.5, duration: 0.3 }}
           className="absolute bottom-8 left-1/2 -translate-x-1/2"
         >
           <motion.div

src/components/sections/case-detail-page.tsx

@@ -85,7 +85,7 @@ function CaseDetailHero({ data }: CaseDetailHeroProps) {
           className="mb-8"
           initial={shouldReduceMotion ? {} : { opacity: 0, y: 30 }}
           animate={{ opacity: 1, y: 0 }}
-          transition={{ duration: 0.8, delay: 0.1, ease: EASE }}
+          transition={{ duration: 0.3, delay: 0.1, ease: EASE }}
         >
           <div
             className="font-sans text-[clamp(56px,12vw,120px)] font-black leading-none tracking-[-2px] mb-2"
@@ -105,7 +105,7 @@ function CaseDetailHero({ data }: CaseDetailHeroProps) {
           className="font-sans text-[clamp(28px,5vw,48px)] font-bold leading-[1.15] tracking-[-0.5px] text-[var(--color-text-primary)] mb-6 max-w-3xl"
           initial={shouldReduceMotion ? {} : { opacity: 0, y: 30 }}
           animate={{ opacity: 1, y: 0 }}
-          transition={{ duration: 0.9, delay: 0.25, ease: EASE }}
+          transition={{ duration: 0.3, delay: 0.25, ease: EASE }}
         >
           {data.title}
         </motion.h1>
@@ -115,7 +115,7 @@ function CaseDetailHero({ data }: CaseDetailHeroProps) {
           style={{ color: 'var(--color-text-secondary)' }}
           initial={shouldReduceMotion ? {} : { opacity: 0, y: 24 }}
           animate={{ opacity: 1, y: 0 }}
-          transition={{ duration: 0.8, delay: 0.4, ease: EASE }}
+          transition={{ duration: 0.3, delay: 0.4, ease: EASE }}
         >
           {data.subtitle}
         </motion.p>
@@ -125,7 +125,7 @@ function CaseDetailHero({ data }: CaseDetailHeroProps) {
           className="grid grid-cols-3 gap-6 sm:gap-10 max-w-lg mb-10"
           initial={shouldReduceMotion ? {} : { opacity: 0, y: 24 }}
           animate={{ opacity: 1, y: 0 }}
-          transition={{ duration: 0.8, delay: 0.55, ease: EASE }}
+          transition={{ duration: 0.3, delay: 0.55, ease: EASE }}
         >
           {data.metrics.slice(1, 4).map((m, i) => (
             <div key={i}>
@@ -147,7 +147,7 @@ function CaseDetailHero({ data }: CaseDetailHeroProps) {
           className="flex flex-wrap gap-x-6 gap-y-3 text-sm mb-10 border-y border-border-primary py-4"
           initial={shouldReduceMotion ? {} : { opacity: 0, y: 24 }}
           animate={{ opacity: 1, y: 0 }}
-          transition={{ duration: 0.8, delay: 0.65, ease: EASE }}
+          transition={{ duration: 0.3, delay: 0.65, ease: EASE }}
         >
           {data.projectDuration && (
             <div style={{ color: 'var(--color-text-secondary)' }}>
@@ -173,7 +173,7 @@ function CaseDetailHero({ data }: CaseDetailHeroProps) {
           className="flex flex-wrap gap-4"
           initial={shouldReduceMotion ? {} : { opacity: 0, y: 24 }}
           animate={{ opacity: 1, y: 0 }}
-          transition={{ duration: 0.8, delay: 0.8, ease: EASE }}
+          transition={{ duration: 0.3, delay: 0.8, ease: EASE }}
         >
           <Button size="lg" asChild>
             <StaticLink href="/contact">