feat: 添加预算管理功能，支持分类预算和重置周期设置，优化用户界面

src/App.vue

@@ -1,6 +1,7 @@
 <script setup>
-import { onMounted } from 'vue'
+import { onMounted, onBeforeUnmount } from 'vue'
 import { RouterView } from 'vue-router'
+import { App } from '@capacitor/app'
 import BottomDock from './components/BottomDock.vue'
 import AddEntryView from './views/AddEntryView.vue'
 import { useTransactionStore } from './stores/transactions'
@@ -9,8 +10,34 @@ import { useUiStore } from './stores/ui'
 const transactionStore = useTransactionStore()
 const uiStore = useUiStore()
 
+let backButtonListener = null
+
 onMounted(() => {
   transactionStore.ensureInitialized()
+
+  // Android 物理返回键：如果新增记录面板打开，则优先关闭面板而不是直接退出应用
+  if (typeof App?.addListener === 'function') {
+    App.addListener('backButton', ({ canGoBack }) => {
+      if (uiStore.addEntryVisible) {
+        uiStore.closeAddEntry()
+      } else if (!canGoBack) {
+        // 这里保留默认行为（由 Capacitor 处理），不强制 exitApp
+      }
+    })
+      .then((handle) => {
+        backButtonListener = handle
+      })
+      .catch(() => {
+        backButtonListener = null
+      })
+  }
+})
+
+onBeforeUnmount(() => {
+  if (backButtonListener && typeof backButtonListener.remove === 'function') {
+    backButtonListener.remove()
+    backButtonListener = null
+  }
 })
 </script>