refactor(ui): unify dialog styles and improve layout consistency

Standardize dialog and panel components across the application.
- Update dialog background to use semantic color tokens
- Adjust FullScreenPanel max-width to 56rem for better alignment
- Add drag region and prevent body scroll in full-screen panels
- Optimize button sizes and spacing in panel headers
- Apply consistent styling to all dialog-based components

src/components/skills/SkillsPage.tsx

@@ -168,7 +168,7 @@ export const SkillsPage = forwardRef<SkillsPageHandle, SkillsPageProps>(
 
         {/* 技能网格（可滚动详情区域） */}
         <div className="flex-1 min-h-0 overflow-y-auto animate-fade-in">
-          <div className="mx-auto max-w-[60rem] px-6 py-4">
+          <div className="mx-auto max-w-[56rem] px-6 py-4">
             {loading ? (
               <div className="flex items-center justify-center h-64">
                 <RefreshCw className="h-8 w-8 animate-spin text-muted-foreground" />