refactor: 拆分 App.vue 为独立组件，修复多项敷衍方案

- 提取 TitleBar、Sidebar、RoamDrawer、CloseModal 四个组件
- App.vue 从 676 行精简至 238 行，职责更清晰
- 修复评论点赞无限+1：改为基于服务端 liked 字段切换
- 修复评论点赞无防重复：添加 likingSet 锁
- 修复评论点赞用本地缓存：likedIds 改为从服务端 likelist API 同步
- 删除 likedIds 写 localStorage 的 watch
- 播放失败/FM加载失败/减少推荐失败添加 showToast 用户提示
- 抽屉遮罩下标题栏按钮保持原色（z-10 提升至遮罩之上）

src/components/CloseModal.vue

@@ -0,0 +1,69 @@
+<template>
+  <Transition name="fade">
+    <div v-if="visible" class="fixed inset-0 z-[60] flex items-center justify-center bg-black/60 backdrop-blur-sm" @click.self="$emit('cancel')">
+      <div class="bg-surface border border-line rounded-2xl shadow-2xl w-80 p-6 select-auto">
+        <h2 class="text-lg font-semibold text-content mb-1">关闭确认</h2>
+        <p class="text-sm text-content-2 mb-5">你希望如何处理？</p>
+        <div class="space-y-2.5 mb-4">
+          <button @click="handleAction('minimize')"
+            class="w-full flex items-center gap-3 px-4 py-3 rounded-xl bg-subtle hover:bg-muted transition text-left">
+            <div class="w-9 h-9 rounded-lg bg-accent-dim flex items-center justify-center flex-shrink-0">
+              <IconMaximize2 class="w-[18px] h-[18px] text-accent-text" />
+            </div>
+            <div>
+              <p class="text-sm font-medium text-content">最小化到托盘</p>
+              <p class="text-xs text-content-3">程序继续在后台运行</p>
+            </div>
+          </button>
+          <button @click="handleAction('exit')"
+            class="w-full flex items-center gap-3 px-4 py-3 rounded-xl bg-subtle hover:bg-muted transition text-left">
+            <div class="w-9 h-9 rounded-lg bg-danger-dim flex items-center justify-center flex-shrink-0">
+              <IconX class="w-[18px] h-[18px] text-danger" />
+            </div>
+            <div>
+              <p class="text-sm font-medium text-content">退出程序</p>
+              <p class="text-xs text-content-3">完全关闭应用程序</p>
+            </div>
+          </button>
+        </div>
+        <label class="flex items-center gap-2 cursor-pointer mb-4 select-none">
+          <input type="checkbox" v-model="dontAskAgain" />
+          <span class="text-xs text-content-2">不再询问，记住我的选择</span>
+        </label>
+        <button @click="$emit('cancel')"
+          class="w-full py-2 rounded-lg bg-muted hover:bg-emphasis text-sm text-content-2 transition">
+          取消
+        </button>
+      </div>
+    </div>
+  </Transition>
+</template>
+
+<script setup lang="ts">
+import { ref } from 'vue';
+import type { CloseAction } from '../stores/settings';
+import IconMaximize2 from '~icons/lucide/maximize-2';
+import IconX from '~icons/lucide/x';
+
+defineProps<{
+  visible: boolean;
+}>();
+
+const emit = defineEmits<{
+  confirm: [action: CloseAction, remember: boolean];
+  cancel: [];
+}>();
+
+const dontAskAgain = ref(false);
+
+function handleAction(action: CloseAction) {
+  emit('confirm', action, dontAskAgain.value);
+}
+</script>
+
+<style scoped>
+.fade-enter-active,
+.fade-leave-active { transition: opacity 0.2s ease; }
+.fade-enter-from,
+.fade-leave-to { opacity: 0; }
+</style>