fix: 修复移动端主题菜单右侧裁剪

src/components/ui/ThemeToggle.vue

@@ -22,7 +22,16 @@ function selectTheme(key: string | number) {
 </script>
 
 <template>
-    <NDropdown v-model:show="open" trigger="click" :value="preference" :options="options" @select="selectTheme">
+    <!-- 菜单右边缘对齐按钮并挂到 body，避免窄屏向右溢出或被外壳裁剪。 -->
+    <NDropdown
+        v-model:show="open"
+        trigger="click"
+        placement="bottom-end"
+        to="body"
+        :value="preference"
+        :options="options"
+        @select="selectTheme"
+    >
         <NButton
             quaternary
             class="theme-toggle icon-button"