fix(snapshot): 修复备份进行中被删除导致容器崩溃的问题

1. checkDone 中 statSync 加 try-catch，文件被删时 reject 而非 uncaught crash
2. 删除 API 禁止删除 RUNNING 状态的任务，返回 409 Conflict
3. compose 补充 restart: unless-stopped，防止异常退出后服务不可用

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

backend/services/docker-compose.2.0-snapshot.yml

@@ -14,6 +14,7 @@ services:
       context: ./snapshot-service
       dockerfile: Dockerfile
     container_name: rwa-snapshot-service-2
+    restart: unless-stopped
     ports:
       - "3199:3199"
     environment:

backend/services/snapshot-service/src/api/controllers/snapshot.controller.ts

@@ -85,6 +85,11 @@ export class SnapshotController {
   @Delete(':id')
   @ApiOperation({ summary: '删除备份' })
   async deleteSnapshot(@Param('id') id: string) {
+    const task = await this.repo.findById(id);
+    if (!task) throw new NotFoundException('备份任务不存在');
+    if (task.status === 'RUNNING') {
+      throw new ConflictException('备份任务正在执行中，无法删除，请等待完成后再操作');
+    }
     await this.orchestrator.deleteSnapshot(id);
     return { message: '备份已删除' };
   }

backend/services/snapshot-service/src/application/services/snapshot-orchestrator.service.ts

@@ -185,6 +185,10 @@ export class SnapshotOrchestratorService implements OnModuleInit {
     const task = await this.repo.findById(taskId);
     if (!task) throw new Error(`任务不存在: ${taskId}`);
 
+    if (task.status === SnapshotStatus.RUNNING) {
+      throw new Error('备份任务正在执行中，无法删除，请等待完成后再操作');
+    }
+
     if (task.storageType === StorageType.LOCAL) {
       this.localStorage.deleteTask(taskId);
     } else if (task.storageType === StorageType.MINIO) {

backend/services/snapshot-service/src/infrastructure/backup/postgres-backup.handler.ts

@@ -119,10 +119,16 @@ export class PostgresBackupHandler implements BackupHandler {
         if (dumpExitCode === null || gzipExitCode === null) return;
 
         if (dumpExitCode === 0 && gzipExitCode === 0) {
+          try {
             const stat = fs.statSync(filePath);
             this.logger.log(`PostgreSQL 备份完成: ${fileName}, 压缩后: ${stat.size} bytes, 原始输出: ${bytesRead} bytes`);
             onProgress(100, 'PostgreSQL 备份完成');
             resolve({ fileName, filePath, fileSize: stat.size });
+          } catch (err) {
+            const msg = `备份文件不可访问 (可能已被删除): ${filePath}`;
+            this.logger.error(msg);
+            reject(new Error(msg));
+          }
         } else {
           const error = `pg_dumpall 退出码: ${dumpExitCode}, gzip 退出码: ${gzipExitCode}, stderr: ${stderrBuffer.slice(-500)}`;
           this.logger.error(error);