fix(admin-service+mobile): 修复 OTA 下载三处 Bug

1. MinIO 内网 hostname 导致 redirect 失效
   → 改为 admin-service 直接流式代理传输文件（streamFile）
   → MinIO 仅绑 127.0.0.1:49000，不对外暴露

2. version_checker.dart 响应解析错误
   → API 返回 {"code":0,"data":{...}} 但代码误把外层 Map 当 VersionInfo
   → 现在正确提取 responseMap["data"] 内层对象

3. VersionInfo.fromJson 在 releaseDate=null 时崩溃
   → releaseDate 改为 nullable (DateTime?)，null-safe 解析
   → 同步修复 version_checker.dart 拼接绝对 downloadUrl

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/services/admin-service/src/application/services/file-storage.service.ts

@@ -56,8 +56,22 @@ export class FileStorageService {
     };
   }
 
-  /** Generate presigned URL for download */
-  async getDownloadUrl(objectName: string): Promise<string> {
-    return this.minio.presignedGetObject(BUCKET, objectName, 24 * 3600);
+  /** Stream file from MinIO to a writable (e.g. Express Response) */
+  async streamFile(objectName: string, destination: NodeJS.WritableStream): Promise<void> {
+    const stream = await this.minio.getObject(BUCKET, objectName);
+    await new Promise<void>((resolve, reject) => {
+      stream.pipe(destination as any);
+      stream.on('end', resolve);
+      stream.on('error', reject);
+    });
+  }
+
+  /** Get file metadata (size) from MinIO */
+  async statFile(objectName: string): Promise<{ size: number; contentType: string }> {
+    const stat = await this.minio.statObject(BUCKET, objectName);
+    return {
+      size: stat.size,
+      contentType: (stat.metaData as any)?.['content-type'] || 'application/octet-stream',
+    };
   }
 }

backend/services/admin-service/src/interface/http/controllers/app-version.controller.ts

@@ -35,13 +35,19 @@ export class AppVersionController {
   }
 
   @Get('download/:id')
-  @ApiOperation({ summary: 'Download app package (regenerates fresh presigned URL each request)' })
+  @ApiOperation({ summary: 'Download app package — streams through service (MinIO not directly exposed)' })
   async downloadVersion(@Param('id') id: string, @Res() res: Response) {
     const version = await this.versionService.getVersion(id);
     if (version.storageKey) {
-      // Generate a fresh 1-hour presigned URL per request — no expiry issue
-      const freshUrl = await this.fileStorage.getDownloadUrl(version.storageKey);
-      return res.redirect(302, freshUrl);
+      // Stream from MinIO through this service — MinIO is not publicly accessible
+      const stat = await this.fileStorage.statFile(version.storageKey);
+      const ext = version.storageKey.split('.').pop() || 'apk';
+      const filename = `app-${version.versionName}.${ext}`;
+      res.setHeader('Content-Type', stat.contentType);
+      res.setHeader('Content-Length', stat.size);
+      res.setHeader('Content-Disposition', `attachment; filename="${filename}"`);
+      await this.fileStorage.streamFile(version.storageKey, res);
+      return;
     }
     return res.redirect(302, version.downloadUrl);
   }

frontend/genex-mobile/lib/core/updater/models/version_info.dart

@@ -24,8 +24,8 @@ class VersionInfo {
   /// 更新日志
   final String? updateLog;
 
-  /// 发布时间
-  final DateTime releaseDate;
+  /// 发布时间（可为空，后台未设置时为 null）
+  final DateTime? releaseDate;
 
   const VersionInfo({
     required this.version,
@@ -36,7 +36,7 @@ class VersionInfo {
     required this.sha256,
     this.forceUpdate = false,
     this.updateLog,
-    required this.releaseDate,
+    this.releaseDate,
   });
 
   factory VersionInfo.fromJson(Map<String, dynamic> json) {
@@ -49,7 +49,9 @@ class VersionInfo {
       sha256: json['sha256'] as String,
       forceUpdate: json['forceUpdate'] as bool? ?? false,
       updateLog: json['updateLog'] as String?,
-      releaseDate: DateTime.parse(json['releaseDate'] as String),
+      releaseDate: json['releaseDate'] != null
+          ? DateTime.parse(json['releaseDate'] as String)
+          : null,
     );
   }
 
@@ -63,7 +65,7 @@ class VersionInfo {
       'sha256': sha256,
       'forceUpdate': forceUpdate,
       'updateLog': updateLog,
-      'releaseDate': releaseDate.toIso8601String(),
+      'releaseDate': releaseDate?.toIso8601String(),
     };
   }
 

frontend/genex-mobile/lib/core/updater/version_checker.dart

@@ -30,6 +30,7 @@ class VersionChecker {
       final response = await _dio.get(
         '/api/v1/app/version/check',
         queryParameters: {
+          'app_type': 'GENEX_MOBILE',
           'platform': 'android',
           'current_version': currentInfo.version,
           'current_version_code': currentInfo.buildNumber,
@@ -37,16 +38,23 @@ class VersionChecker {
       );
 
       if (response.statusCode == 200 && response.data != null) {
-        final data = response.data is Map<String, dynamic>
-            ? response.data as Map<String, dynamic>
-            : (response.data['data'] as Map<String, dynamic>?) ?? response.data;
+        // API wraps response: {"code":0,"data":{...}} — extract the inner object
+        final responseMap = response.data as Map<String, dynamic>;
+        final data = (responseMap['data'] as Map<String, dynamic>?) ?? responseMap;
 
-        final needUpdate = data['needUpdate'] as bool? ?? true;
+        final needUpdate = data['needUpdate'] as bool? ?? false;
         if (!needUpdate) {
           debugPrint('[VersionChecker] 无需更新');
           return null;
         }
-        return VersionInfo.fromJson(data);
+
+        // Fix relative downloadUrl → prepend apiBaseUrl for DownloadManager
+        final rawUrl = data['downloadUrl'] as String? ?? '';
+        final fixedData = (rawUrl.isNotEmpty && !rawUrl.startsWith('http'))
+            ? (Map<String, dynamic>.from(data)..['downloadUrl'] = '$apiBaseUrl$rawUrl')
+            : data;
+
+        return VersionInfo.fromJson(fixedData);
       }
       return null;
     } catch (e) {