Tab切换动画:横向轻扫+淡入 + 活跃Tab下划线渐变

- 活跃Tab下方添加墨色渐变下划线动画(从中心向两侧展开)
- 页面内容切换时横向轻扫+淡入效果(0.3s)
- 使用 key={location.pathname} 触发重新渲染动画

Co-Authored-By: new-provider/LongCat-2.0 <<EMAIL>>
)

frontend/src/admin/AdminLayout.tsx

@@ -227,9 +227,9 @@ export default function AdminLayout() {
             to="/admin"
             end
             className={({ isActive }) =>
-              `flex min-h-[40px] items-center gap-2.5 border-l-4 px-3 text-sm transition-colors ${
+              `flex min-h-[40px] items-center gap-2.5 border-l-4 px-3 pb-1 text-sm transition-all duration-300 ${
                 isActive
-                  ? 'border-press bg-press-wash/60 font-medium text-press'
+                  ? 'border-press bg-press-wash/60 font-medium text-press nav-tab-active'
                   : 'border-transparent text-ink-500 hover:bg-paper-100 hover:text-ink-900'
               }`
             }
@@ -249,9 +249,9 @@ export default function AdminLayout() {
                     <NavLink
                       to={item.to}
                       className={({ isActive }) =>
-                        `flex min-h-[40px] items-center gap-2.5 border-l-4 px-3 text-sm transition-colors ${
+                        `flex min-h-[40px] items-center gap-2.5 border-l-4 px-3 pb-1 text-sm transition-all duration-300 ${
                           isActive
-                            ? 'border-press bg-press-wash/60 font-medium text-press'
+                            ? 'border-press bg-press-wash/60 font-medium text-press nav-tab-active'
                             : 'border-transparent text-ink-500 hover:bg-paper-100 hover:text-ink-900'
                         }`
                       }
@@ -282,8 +282,8 @@ export default function AdminLayout() {
       </aside>
 
       {/* ── 主内容区 ── */}
-      <main className="flex-1 overflow-y-auto p-4 lg:p-8">
-        <div className="mx-auto max-w-6xl">
+      <main className="flex-1 overflow-y-auto p-4 lg:p-8" key={location.pathname}>
+        <div className="mx-auto max-w-6xl page-content-enter">
           <Outlet />
         </div>
       </main>