feat(version-service): add GET /api/app/version/check endpoint for Flutter app

Flutter VersionChecker was calling GET /api/app/version/check but this
endpoint didn't exist — only the admin CRUD /api/v1/versions was there.

New: AppVersionCheckController (@Controller('api/app/version'))
  GET /api/app/version/check?platform=android&current_version_code=N
  - Finds latest enabled version for the platform (highest buildNumber)
  - Returns { needUpdate: false } when already up to date
  - Returns full VersionInfo payload when update is available

Response fields match Flutter VersionInfo.fromJson exactly:
  needUpdate, version, versionCode, downloadUrl, fileSize,
  fileSizeFriendly (computed), sha256 (empty — not stored),
  forceUpdate, updateLog, releaseDate

Also: AppVersionRepository.findLatestEnabled(platform) — queries all
enabled versions for platform, picks the one with the highest buildNumber
(parsed as int, robust against varchar storage).

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

packages/services/version-service/src/infrastructure/repositories/app-version.repository.ts

@@ -47,4 +47,23 @@ export class AppVersionRepository {
   async delete(id: string): Promise<void> {
     await this.repo.delete(id);
   }
+
+  /** 查询指定平台最新启用版本（buildNumber 最大的已启用版本） */
+  async findLatestEnabled(platform: Platform): Promise<AppVersion | null> {
+    const versions = await this.repo
+      .createQueryBuilder('v')
+      .where('v.platform = :platform', { platform })
+      .andWhere('v.isEnabled = true')
+      .orderBy('v.createdAt', 'DESC')
+      .getMany();
+
+    if (versions.length === 0) return null;
+
+    // 找 buildNumber（整数）最大的版本，兼容字符串存储
+    return versions.reduce((best, cur) => {
+      const bestCode = parseInt(best.buildNumber, 10) || 0;
+      const curCode = parseInt(cur.buildNumber, 10) || 0;
+      return curCode > bestCode ? cur : best;
+    });
+  }
 }

packages/services/version-service/src/interfaces/rest/controllers/app-version-check.controller.ts

@@ -0,0 +1,70 @@
+import { Controller, Get, Query } from '@nestjs/common';
+import { AppVersionRepository } from '../../../infrastructure/repositories/app-version.repository';
+import { Platform } from '../../../domain/entities/app-version.entity';
+
+/**
+ * 公开接口：供 IT0 App 检查是否有新版本
+ * GET /api/app/version/check
+ *
+ * 查询参数:
+ *   platform           - 平台 (android | ios)，不区分大小写
+ *   current_version_code - 当前安装的构建号 (build number)
+ *
+ * 响应格式（与 Flutter VersionInfo.fromJson 完全对应）:
+ *   needUpdate    bool    - 是否需要更新
+ *   version       string  - 最新版本号 (versionName, e.g. "1.0.0")
+ *   versionCode   int     - 最新构建号 (buildNumber as int)
+ *   downloadUrl   string  - APK 下载地址
+ *   fileSize      int     - 文件大小（字节）
+ *   fileSizeFriendly string - 友好显示 (e.g. "146.9 MB")
+ *   sha256        string  - SHA-256（暂未存储，返回空串）
+ *   forceUpdate   bool    - 是否强制更新
+ *   updateLog     string? - 更新日志
+ *   releaseDate   string  - 发布时间 ISO 字符串
+ */
+@Controller('api/app/version')
+export class AppVersionCheckController {
+  constructor(private readonly versionRepo: AppVersionRepository) {}
+
+  @Get('check')
+  async check(
+    @Query('platform') platform: string,
+    @Query('current_version_code') currentVersionCode?: string,
+  ) {
+    const platformEnum = ((platform || 'android').toUpperCase()) as Platform;
+    const latest = await this.versionRepo.findLatestEnabled(platformEnum);
+
+    if (!latest) {
+      return { needUpdate: false };
+    }
+
+    const latestCode = parseInt(latest.buildNumber, 10) || 0;
+    const currentCode = parseInt(currentVersionCode || '0', 10) || 0;
+
+    if (latestCode <= currentCode) {
+      return { needUpdate: false };
+    }
+
+    const fileSizeNum = Number(latest.fileSize) || 0;
+
+    return {
+      needUpdate: true,
+      version: latest.versionName,
+      versionCode: latestCode,
+      downloadUrl: latest.downloadUrl || '',
+      fileSize: fileSizeNum,
+      fileSizeFriendly: formatFileSize(fileSizeNum),
+      sha256: '',          // version-service 不存储 sha256，留空
+      forceUpdate: latest.isForceUpdate,
+      updateLog: latest.changelog ?? null,
+      releaseDate: (latest.releaseDate ?? latest.createdAt).toISOString(),
+    };
+  }
+}
+
+function formatFileSize(bytes: number): string {
+  if (bytes >= 1024 * 1024 * 1024) return `${(bytes / (1024 * 1024 * 1024)).toFixed(1)} GB`;
+  if (bytes >= 1024 * 1024) return `${(bytes / (1024 * 1024)).toFixed(1)} MB`;
+  if (bytes >= 1024) return `${(bytes / 1024).toFixed(1)} KB`;
+  return `${bytes} B`;
+}

packages/services/version-service/src/version.module.ts

@@ -5,6 +5,7 @@ import { DatabaseModule } from '@it0/database';
 import { AppVersion } from './domain/entities/app-version.entity';
 import { AppVersionRepository } from './infrastructure/repositories/app-version.repository';
 import { VersionController } from './interfaces/rest/controllers/version.controller';
+import { AppVersionCheckController } from './interfaces/rest/controllers/app-version-check.controller';
 
 @Module({
   imports: [
@@ -12,7 +13,7 @@ import { VersionController } from './interfaces/rest/controllers/version.control
     DatabaseModule.forRoot(),
     TypeOrmModule.forFeature([AppVersion]),
   ],
-  controllers: [VersionController],
+  controllers: [VersionController, AppVersionCheckController],
   providers: [AppVersionRepository],
 })
 export class VersionModule {}