feat(design): Vibe design optimization — Hero, Bento grids, trust layer, narrative

升级全站体验：首页 Hero 改为产品视觉 + 单一 CTA 转化布局；产品矩阵/服务/方案改
为 Bento 非对称网格（ERP 2x2 大卡 + BI 1x2）；补齐信任层（可验证信号 + 来源标注）
与「问题→方法→结果」章节式叙事；新增 hero-product-visual 与 bento-grid 可复用组件；
统一动效与品牌视觉资产。新增对应单测、UJ-11 用户旅程测试并更新视觉回归基线快照。

src/app/(marketing)/solutions/solutions-content-v3.tsx

@@ -108,7 +108,7 @@ function HeroSection() {
   );
 }
 
-function SolutionCard({ solution, index, products }: { solution: Solution; index: number; products?: Product[] }) {
+function SolutionCard({ solution, index, products, featured = false }: { solution: Solution; index: number; products?: Product[]; featured?: boolean }) {
   const productLookup = products ?? [];
   const Icon = INDUSTRY_ICONS[solution.industry] || Factory;
   const recommendedProductNames = (solution.recommendedProducts ?? [])
@@ -117,6 +117,9 @@ function SolutionCard({ solution, index, products }: { solution: Solution; index
 
   return (
     <motion.div
+      data-testid={`solution-card-${solution.id}`}
+      data-featured={featured ? 'true' : 'false'}
+      className={featured ? 'md:col-span-2 bg-white' : 'md:col-span-1 bg-white'}
       initial={{ opacity: 0, y: 30 }}
       whileInView={{ opacity: 1, y: 0 }}
       viewport={{ once: true, margin: '-60px' }}
@@ -124,7 +127,7 @@ function SolutionCard({ solution, index, products }: { solution: Solution; index
     >
       <StaticLink
         href={`/solutions/${solution.id}`}
-        className="group relative block transition-all duration-500 hover:bg-bg-secondary hover:shadow-lg hover:-translate-y-1 bg-white border border-border-primary hover:border-brand/20"
+        className="group relative block transition-all duration-300 hover:bg-bg-secondary hover:shadow-lg hover:-translate-y-1 bg-white border border-border-primary hover:border-brand/20 after:absolute after:bottom-0 after:left-0 after:h-0.5 after:w-full after:origin-left after:scale-x-0 after:bg-brand after:transition-transform after:duration-300 group-hover:after:scale-x-100"
       >
         <div className="relative z-10 p-8 sm:p-10 md:p-12">
           <div className="flex items-center gap-3 mb-6">
@@ -195,7 +198,7 @@ function SolutionsGridSection({ solutions, products }: { solutions: Solution[];
 
         <div className="grid md:grid-cols-2 gap-px bg-border-primary">
           {solutions.map((solution, index) => (
-            <SolutionCard key={solution.id} solution={solution} index={index} products={products} />
+            <SolutionCard key={solution.id} solution={solution} index={index} products={products} featured={index === 0} />
           ))}
         </div>
       </div>