接入原生壳文本文件导入能力

新增 file.importText HostBridge 契约和 H5 facade

移动端通过 Expo DocumentPicker 读取受控文本文件

桌面端通过 Tauri 文件选择框读取受控文本文件

更新壳能力检查、测试、方案文档和共享决策记录

apps/mobile-shell/scripts/check-config.mjs

@@ -131,6 +131,7 @@ for (const snippet of [
 
 for (const dependency of [
   'expo-file-system',
+  'expo-document-picker',
   'expo-image-picker',
   'expo-network',
   'expo-notifications',
@@ -177,6 +178,7 @@ if (Array.isArray(notificationsPlugin)) {
 
 for (const snippet of [
   'file.exportText',
+  'file.importText',
   'file.exportImage',
   'file.importImage',
   'clipboard.readText',
@@ -188,6 +190,7 @@ for (const snippet of [
   'Notifications.getPermissionsAsync',
   'Notifications.requestPermissionsAsync',
   'Sharing.shareAsync',
+  'DocumentPicker.getDocumentAsync',
   'Clipboard.getStringAsync',
   'ImagePicker.launchImageLibraryAsync',
   'ImagePicker.requestMediaLibraryPermissionsAsync',
@@ -223,6 +226,7 @@ for (const capability of [
   'clipboard.writeText',
   'clipboard.readText',
   'file.exportText',
+  'file.importText',
   'file.exportImage',
   'file.importImage',
   'haptics.impact',