fix: 修复输入框和按钮在暗色模式下的样式问题

- 为 :root 和 .dark 添加 color-scheme，使浏览器表单控件默认样式适配暗色模式
- 将 bg-primary 搭配 text-white 的按钮改为 text-primary-foreground
- 替换残留的 hover:bg-blue-700、text-blue-500、bg-gray-200 等硬编码颜色
- 同步更新 TextInputArea 单元测试

components/PageSkeleton.tsx

@@ -17,13 +17,13 @@ function DashboardCardSkeleton() {
     <div className="rounded-xl border border-border p-5 h-[100px]">
       <div className="flex justify-between items-start">
         <div className="flex gap-3 items-center">
-          <div className="w-10 h-10 rounded-lg bg-gray-200 animate-pulse" />
+          <div className="w-10 h-10 rounded-lg bg-muted animate-pulse" />
           <div>
-            <div className="w-24 h-5 bg-gray-200 rounded animate-pulse" />
-            <div className="w-32 h-3.5 bg-gray-200 rounded animate-pulse mt-1.5" />
+            <div className="w-24 h-5 bg-muted rounded animate-pulse" />
+            <div className="w-32 h-3.5 bg-muted rounded animate-pulse mt-1.5" />
           </div>
         </div>
-        <div className="w-3 h-3 rounded-full bg-gray-200 animate-pulse" />
+        <div className="w-3 h-3 rounded-full bg-muted animate-pulse" />
       </div>
     </div>
   );
@@ -36,21 +36,21 @@ function ToolPageSkeleton() {
   return (
     <div className="p-5">
       {/* 标题区域 */}
-      <div className="w-44 h-7 bg-gray-200 rounded animate-pulse mb-4" />
+      <div className="w-44 h-7 bg-muted rounded animate-pulse mb-4" />
 
       {/* 输入区域 */}
-      <div className="w-full h-[120px] bg-gray-200 rounded-xl animate-pulse mb-4" />
+      <div className="w-full h-[120px] bg-muted rounded-xl animate-pulse mb-4" />
 
       {/* 控制栏 */}
       <div className="flex gap-2 mb-4">
-        <div className="w-24 h-9 bg-gray-200 rounded-lg animate-pulse" />
-        <div className="w-20 h-9 bg-gray-200 rounded-lg animate-pulse" />
+        <div className="w-24 h-9 bg-muted rounded-lg animate-pulse" />
+        <div className="w-20 h-9 bg-muted rounded-lg animate-pulse" />
         <div className="flex-1" />
-        <div className="w-22 h-9 bg-gray-200 rounded-lg animate-pulse" />
+        <div className="w-22 h-9 bg-muted rounded-lg animate-pulse" />
       </div>
 
       {/* 结果区域 */}
-      <div className="w-full h-[160px] bg-gray-200 rounded-xl animate-pulse" />
+      <div className="w-full h-[160px] bg-muted rounded-xl animate-pulse" />
     </div>
   );
 }

components/TextInputArea.tsx

@@ -152,7 +152,7 @@ function ActionButton({
     typeof action.disabled === 'function' ? action.disabled(value) : action.disabled || !value;
 
   const typeClasses: Record<string, string> = {
-    primary: 'bg-primary text-white hover:bg-primary/90',
+    primary: 'bg-primary text-primary-foreground hover:bg-primary/90',
     danger: 'text-red-600 hover:bg-red-500/10',
     default: 'text-muted-foreground hover:bg-muted',
   };

components/__tests__/TextInputArea.test.tsx

@@ -334,7 +334,7 @@ describe('TextInputArea 组件', () => {
       );
 
       const btn = screen.getByText('主要');
-      expect(btn).toHaveClass('bg-primary', 'text-white');
+      expect(btn).toHaveClass('bg-primary', 'text-primary-foreground');
     });
   });