feat: 添加 PWA 安装支持，包含安装提示和 iOS 指导页面

src/components/pwa-install-button/index.vue

@@ -0,0 +1,42 @@
+<script setup lang="ts">
+import { alertController, modalController } from "@ionic/vue";
+import IOSInstallGuide from "./ios-install-guide.vue";
+
+const { t } = useI18n();
+
+const {
+  showInstallButton,
+  promptInstall,
+  isIOS,
+} = usePWAInstall();
+
+async function handleInstall() {
+  const result = await promptInstall();
+
+  if (result.outcome === "accepted") {
+    const alert = await alertController.create({
+      header: t("pwa.install.success"),
+      message: t("pwa.install.successMessage"),
+      buttons: [t("common.ok")],
+    });
+    await alert.present();
+  }
+  else if (result.outcome === "ios-instruction") {
+    const modal = await modalController.create({
+      component: IOSInstallGuide,
+    });
+    await modal.present();
+  }
+}
+</script>
+
+<template>
+  <IonButton
+    v-if="showInstallButton"
+    expand="block"
+    @click="handleInstall"
+  >
+    <IIcBaselineDownload class="mr-2" />
+    {{ isIOS ? t('pwa.install.addToHomeScreen') : t('pwa.install.installApp') }}
+  </IonButton>
+</template>