feat(home): Hero 右侧看板 Absorb 层渐进描边

hero-product-visual 升级为客户端组件，趋势线改用 stroke-dashoffset 渐进描边：
滚动入视触发、600ms ease-ink 绘出，填充/端点同步淡入，补齐参考埃森哲的
Glance/Skim/Absorb 三层交互模型。reduced-motion 首帧即静态完整线、零动画；
IntersectionObserver 不可用时降级静态。刻意未做 KPI count-up（格式化串解析 hacky
且偏装饰，与动效克制偏好冲突）。

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

src/components/sections/hero-product-visual.test.tsx

@@ -0,0 +1,27 @@
+import { describe, it, expect, jest } from '@jest/globals';
+import { render } from '@testing-library/react';
+import '@testing-library/jest-dom';
+import HeroProductVisual from './hero-product-visual';
+
+jest.mock('@/hooks/use-reduced-motion', () => ({
+  useReducedMotion: jest.fn(() => false),
+}));
+
+describe('HeroProductVisual - Absorb 层（渐进描边）', () => {
+  it('renders the brand-red trend line path', () => {
+    render(<HeroProductVisual />);
+    const path = document.querySelector('.hero-trend-line');
+    expect(path).toBeInTheDocument();
+    expect(path).toHaveAttribute('stroke', 'var(--color-brand)');
+  });
+
+  it('renders the trend line statically (no draw animation) under reduced motion', () => {
+    const { useReducedMotion } = require('@/hooks/use-reduced-motion');
+    (useReducedMotion as jest.Mock).mockReturnValue(true);
+    render(<HeroProductVisual />);
+    const path = document.querySelector('.hero-trend-line') as SVGPathElement;
+    expect(path).toBeInTheDocument();
+    // reduced-motion：入场即为完整描边（strokeDashoffset = 0），不播放描边动画
+    expect(path.style.strokeDashoffset).toBe('0');
+  });
+});

src/components/sections/hero-product-visual.tsx

@@ -1,5 +1,9 @@
+'use client';
+
+import { useEffect, useRef, useState } from 'react';
 import { TrendingUp, ArrowUpRight, ArrowDownRight } from 'lucide-react';
 import { cn } from '@/lib/utils';
+import { useReducedMotion } from '@/hooks/use-reduced-motion';
 
 // 抽象数据可视化示意（示例数据）——作为品牌「数据驱动」能力的视觉表达，不含具体产品 UI 外壳
 const KPIS = [
@@ -19,9 +23,42 @@ function TrendBadge({ trend, label }: { trend: 'up' | 'down'; label: string }) {
   );
 }
 
+const EASE_INK = 'cubic-bezier(0.22, 1, 0.36, 1)';
+// 描边路径长度上限（宽松覆盖实际路径，确保 offset 动画完整绘制整条线）
+const TREND_PATH_LENGTH = 600;
+
 export function HeroProductVisual({ className }: { className?: string }) {
+  const rootRef = useRef<HTMLDivElement>(null);
+  const reduceMotion = useReducedMotion();
+  // reduced-motion：首帧即为静态完整线，杜绝任何一闪
+  const [drawn, setDrawn] = useState(reduceMotion);
+
+  useEffect(() => {
+    if (reduceMotion) {
+      setDrawn(true);
+      return;
+    }
+    const el = rootRef.current;
+    if (!el || typeof IntersectionObserver === 'undefined') {
+      setDrawn(true); // 无 IO 支持的降级：直接静态呈现完整线
+      return;
+    }
+    const io = new IntersectionObserver(
+      (entries) => {
+        if (entries.some((e) => e.isIntersecting)) {
+          setDrawn(true);
+          io.disconnect();
+        }
+      },
+      { threshold: 0.25 },
+    );
+    io.observe(el);
+    return () => io.disconnect();
+  }, [reduceMotion]);
+
   return (
     <div
+      ref={rootRef}
       data-testid="hero-product-visual"
       role="img"
       aria-label="数据驱动可视化示意（示例数据）"
@@ -49,7 +86,7 @@ export function HeroProductVisual({ className }: { className?: string }) {
         ))}
       </div>
 
-      {/* 趋势图：品牌色曲线 + 渐变填充 */}
+      {/* 趋势图：品牌色曲线 + 渐变填充（Absorb 层：滚动入视时曲线渐进描边，数据「长出来」） */}
       <div className="mt-3 border border-border-primary bg-bg-primary p-4">
         <div className="mb-3 flex items-center justify-between">
           <span className="text-xs font-semibold text-ink">数据增长趋势</span>
@@ -73,17 +110,40 @@ export function HeroProductVisual({ className }: { className?: string }) {
           <path
             d="M0,104 C36,96 56,80 88,82 C120,84 144,60 176,58 C208,56 232,38 264,40 C296,42 320,24 360,20 L360,120 L0,120 Z"
             fill="url(#hero-visual-fill)"
+            style={{
+              opacity: drawn ? 1 : 0,
+              transition: reduceMotion ? undefined : 'opacity 600ms ease 120ms',
+            }}
           />
           <path
+            className="hero-trend-line"
             d="M0,104 C36,96 56,80 88,82 C120,84 144,60 176,58 C208,56 232,38 264,40 C296,42 320,24 360,20"
             fill="none"
             stroke="var(--color-brand)"
             strokeWidth="2.5"
             strokeLinecap="round"
+            style={{
+              strokeDasharray: TREND_PATH_LENGTH,
+              strokeDashoffset: drawn ? 0 : TREND_PATH_LENGTH,
+              transition: reduceMotion
+                ? undefined
+                : `stroke-dashoffset 600ms ${EASE_INK}`,
+            }}
+          />
+          <circle
+            cx="360"
+            cy="20"
+            r="4"
+            fill="var(--color-brand)"
+            style={{
+              opacity: drawn ? 1 : 0,
+              transition: reduceMotion ? undefined : 'opacity 400ms ease 520ms',
+            }}
           />
-          <circle cx="360" cy="20" r="4" fill="var(--color-brand)" />
         </svg>
       </div>
     </div>
   );
 }
+
+export default HeroProductVisual;