feat: 优化前端布局为流动式响应式设计

- 移除 Dashboard max-width 限制，充分利用屏幕空间
- Summary Cards 和 Target Cards 改为 Flexbox wrap 流动布局
- 卡片固定宽度 280px，根据页面宽度自动调整单行数量
- 添加平滑过渡动画效果（0.3s ease）
- 移除移动端媒体查询覆盖规则
- 同步更新 card-dashboard 规格文档

src/web/styles.css

@@ -22,9 +22,8 @@ body {
 }
 
 .dashboard {
-  max-width: 1200px;
-  margin: 0 auto;
   padding: 32px 24px;
+  width: 100%;
 }
 
 .dashboard-header {
@@ -54,18 +53,28 @@ body {
 }
 
 .summary-cards {
-  display: grid;
-  grid-template-columns: repeat(3, 1fr);
+  display: flex;
+  flex-wrap: wrap;
   gap: 16px;
   margin-bottom: 32px;
 }
 
 .summary-card {
+  width: 280px;
+  flex-shrink: 0;
   padding: 20px;
   border: 1px solid rgba(49, 83, 126, 0.12);
   border-radius: 16px;
   background: rgba(255, 255, 255, 0.85);
   box-shadow: 0 4px 16px rgba(34, 57, 91, 0.08);
+  transition:
+    transform 0.3s ease,
+    box-shadow 0.3s ease;
+}
+
+.summary-card:hover {
+  box-shadow: 0 8px 32px rgba(34, 57, 91, 0.12);
+  transform: translateY(-4px);
 }
 
 .card-value {
@@ -118,12 +127,14 @@ body {
 }
 
 .card-grid {
-  display: grid;
-  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
+  display: flex;
+  flex-wrap: wrap;
   gap: 16px;
 }
 
 .target-card {
+  width: 280px;
+  flex-shrink: 0;
   padding: 16px;
   border: 1px solid rgba(49, 83, 126, 0.12);
   border-radius: 12px;
@@ -131,8 +142,8 @@ body {
   box-shadow: 0 2px 8px rgba(34, 57, 91, 0.06);
   cursor: pointer;
   transition:
-    box-shadow 0.15s,
-    transform 0.15s;
+    box-shadow 0.3s ease,
+    transform 0.3s ease;
 }
 
 .target-card:hover {
@@ -566,18 +577,6 @@ body {
     padding: 16px;
   }
 
-  .summary-cards {
-    grid-template-columns: repeat(2, 1fr);
-  }
-
-  .card-grid {
-    grid-template-columns: 1fr;
-  }
-
-  .target-card {
-    width: 100%;
-  }
-
   .modal-content {
     width: 95vw;
     max-height: 90vh;