Phase 3: Redesign homepage + natural Thai text

- Add use cases section with 4 scenario cards (news, policy, business, fiction)
- Rewrite Thai home section text to be natural (not translated from Chinese)
- Add use case locale keys for th/en/zh
- Add CSS for use cases grid with hover effects

frontend/src/views/Home.vue

@@ -53,6 +53,41 @@
         </div>
       </section>
 
+      <!-- Use Cases Section -->
+      <section class="usecases-section">
+        <h2 class="usecases-title">{{ $t('home.useCases') }}</h2>
+        <div class="usecases-grid">
+          <div class="usecase-card">
+            <div class="usecase-icon">📰</div>
+            <div class="usecase-content">
+              <div class="usecase-name">{{ $t('home.useCase1Title') }}</div>
+              <div class="usecase-desc">{{ $t('home.useCase1Desc') }}</div>
+            </div>
+          </div>
+          <div class="usecase-card">
+            <div class="usecase-icon">📋</div>
+            <div class="usecase-content">
+              <div class="usecase-name">{{ $t('home.useCase2Title') }}</div>
+              <div class="usecase-desc">{{ $t('home.useCase2Desc') }}</div>
+            </div>
+          </div>
+          <div class="usecase-card">
+            <div class="usecase-icon">📢</div>
+            <div class="usecase-content">
+              <div class="usecase-name">{{ $t('home.useCase3Title') }}</div>
+              <div class="usecase-desc">{{ $t('home.useCase3Desc') }}</div>
+            </div>
+          </div>
+          <div class="usecase-card">
+            <div class="usecase-icon">📖</div>
+            <div class="usecase-content">
+              <div class="usecase-name">{{ $t('home.useCase4Title') }}</div>
+              <div class="usecase-desc">{{ $t('home.useCase4Desc') }}</div>
+            </div>
+          </div>
+        </div>
+      </section>
+
       <!-- 下半部分：双栏布局 -->
       <section class="dashboard-section">
         <!-- 左栏：状态与步骤 -->
@@ -540,6 +575,64 @@ const startSimulation = () => {
   border-color: var(--orange);
 }
 
+/* Use Cases Section */
+.usecases-section {
+  padding: 40px 60px;
+  background: #fff;
+}
+
+.usecases-title {
+  font-size: 1.5rem;
+  font-weight: 700;
+  color: #1a1a1a;
+  margin-bottom: 24px;
+  text-align: center;
+}
+
+.usecases-grid {
+  display: grid;
+  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
+  gap: 16px;
+  max-width: 1000px;
+  margin: 0 auto;
+}
+
+.usecase-card {
+  display: flex;
+  align-items: flex-start;
+  gap: 14px;
+  padding: 20px;
+  background: #F8F9FA;
+  border-radius: 12px;
+  border: 1px solid #E5E7EB;
+  transition: border-color 0.2s, box-shadow 0.2s;
+  cursor: default;
+}
+
+.usecase-card:hover {
+  border-color: #FF6B35;
+  box-shadow: 0 2px 12px rgba(255, 107, 53, 0.08);
+}
+
+.usecase-icon {
+  font-size: 1.8rem;
+  line-height: 1;
+  flex-shrink: 0;
+}
+
+.usecase-name {
+  font-weight: 600;
+  font-size: 0.95rem;
+  color: #1a1a1a;
+  margin-bottom: 4px;
+}
+
+.usecase-desc {
+  font-size: 0.82rem;
+  color: #666;
+  line-height: 1.5;
+}
+
 /* Dashboard 双栏布局 */
 .dashboard-section {
   display: flex;