feat(web): move three pillars inside the product overview section

- Merged 幸福支柱 pillars-grid into #product section after product-intro
- Removed standalone #pillars section
- Removed nav link for #pillars (now accessible via 浠艾福)

web/index.html

@@ -106,7 +106,7 @@
         <ul class="nav-list">
           <li><a href="#about" class="nav-link">关于我们</a></li>
           <li><a href="#product" class="nav-link">浠艾福</a></li>
-          <li><a href="#pillars" class="nav-link">幸福支柱</a></li>
+
           <li><a href="#products" class="nav-link">核心能力</a></li>
           <li><a href="#wuxing" class="nav-link">能量维度</a></li>
           <li><a href="#features" class="nav-link">核心功能</a></li>
@@ -245,24 +245,10 @@
               <span class="stat-num">6</span>
               <span class="stat-label">AI 技术应用</span>
             </a>
-          </div>
         </div>
-    </div>
-  </section>
-
-  <!-- ==================== Three Pillars of Happiness ==================== -->
-  <section class="section section-pillars" id="pillars">
-    <div class="container">
-      <div class="section-header">
-        <span class="section-tag">目标体系</span>
-        <h2 class="section-title">幸福支柱</h2>
-        <p class="section-subtitle">目标指引方向 · 五维落地执行</p>
-        <p class="section-desc">
-          三大目标支柱指引家庭幸福方向，扩展至五维行动体系落地执行。
-          每一支柱映射两个核心维度，从愿景到行动，让幸福可感知、可衡量、可持续。
-        </p>
       </div>
 
+      <!-- 幸福支柱 -->
       <div class="pillars-grid">
         <!-- 衣食无忧 -->
         <div class="pillar-card pillar-card--material reveal">