feat: add EventList and HeaderBar with organize/undo/download

src/App.vue

@@ -1,6 +1,8 @@
 <script setup>
 import { useCalendar } from './composables/useCalendar.js'
 import DropZone from './components/DropZone.vue'
+import HeaderBar from './components/HeaderBar.vue'
+import EventList from './components/EventList.vue'
 
 const { isLoaded } = useCalendar()
 </script>
@@ -9,12 +11,16 @@ const { isLoaded } = useCalendar()
   <div class="app">
     <header class="app-header">
       <h1>📅 ICS 日程整理器</h1>
+      <HeaderBar />
     </header>
     <main class="app-main">
       <DropZone v-if="!isLoaded" />
-      <div v-else class="placeholder">
-        <p>文件已加载（列表与编辑器待实现）</p>
-      </div>
+      <template v-else>
+        <EventList />
+        <div class="detail-area">
+          <div class="empty">从左侧选择一个日程进行编辑</div>
+        </div>
+      </template>
     </main>
   </div>
 </template>
@@ -38,11 +44,10 @@ body {
 }
 .app-header h1 { font-size: 18px; font-weight: 600; }
 .app-main { flex: 1; display: flex; overflow: hidden; }
-.placeholder {
-  flex: 1;
-  display: flex;
-  align-items: center;
-  justify-content: center;
+.detail-area { flex: 1; overflow-y: auto; }
+.empty {
+  text-align: center;
+  padding: 60px 20px;
   color: #95a5a6;
 }
 </style>