接入原生壳文档导入

新增 HostBridge file.importDocument 契约与文档 MIME 边界

实现 Expo 与 Tauri 受控文档选择和 base64 返回

创作 Agent 工作台优先使用文档导入并保留文本导入兜底

同步宿主壳门禁、测试、架构文档和共享记忆

scripts/check-native-shells.mjs

@@ -32,6 +32,7 @@ const h5HostBridgeScannedFacadeImports = new Set([
   'getHostNetworkStatus',
   'getNativeAppHostRuntime',
   'importHostAudioFile',
+  'importHostDocumentFile',
   'importHostImageFile',
   'importHostTextFile',
   'navigateHostNativePage',
@@ -1012,10 +1013,10 @@ function assertNativeShellCapabilityPlan() {
       'navigation.canGoBack',
       ...sharedMethods.slice(8, 12),
       'network.statusChanged',
-      ...sharedMethods.slice(12, 21),
-      sharedMethods[21],
+      ...sharedMethods.slice(12, 22),
+      sharedMethods[22],
       'file.imageDropped',
-      ...sharedMethods.slice(22),
+      ...sharedMethods.slice(23),
     ],
     'native shell documented method table',
   );