feat(platform): Implement platform infrastructure with cloud-native support

- Add storage service (LocalAdapter + OSSAdapter stub)
- Add database connection pool with graceful shutdown
- Add logging system with winston (JSON format)
- Add environment config management
- Add async job queue (MemoryQueue + DatabaseQueue stub)
- Add cache service (MemoryCache + RedisCache stub)
- Add health check endpoints for SAE
- Add monitoring metrics for DB, memory, API

Key Features:
- Zero-code switching between local and cloud environments
- Adapter pattern for multi-environment support
- Backward compatible with legacy modules
- Ready for Aliyun Serverless deployment

Related: Platform Infrastructure Planning (docs/09-鏋舵瀯瀹炴柦/04-骞冲彴鍩虹璁炬柦瑙勫垝.md)

backend/src/common/jobs/JobFactory.ts

@@ -0,0 +1,82 @@
+import { JobQueue } from './types.js'
+import { MemoryQueue } from './MemoryQueue.js'
+
+/**
+ * 任务队列工厂类
+ * 
+ * 根据环境变量自动选择队列实现：
+ * - QUEUE_TYPE=memory: 使用MemoryQueue（内存队列）
+ * - QUEUE_TYPE=database: 使用DatabaseQueue（数据库队列，待实现）
+ * 
+ * 零代码切换：
+ * - 本地开发：不配置QUEUE_TYPE，默认使用memory
+ * - 云端部署：配置QUEUE_TYPE=database（多实例共享）
+ * 
+ * @example
+ * ```typescript
+ * import { jobQueue } from '@/common/jobs'
+ * 
+ * // 业务代码不关心是memory还是database
+ * const job = await jobQueue.push('asl:screening', { projectId: 123 })
+ * ```
+ */
+export class JobFactory {
+  private static instance: JobQueue | null = null
+
+  /**
+   * 获取任务队列实例（单例模式）
+   */
+  static getInstance(): JobQueue {
+    if (!this.instance) {
+      this.instance = this.createQueue()
+    }
+    return this.instance
+  }
+
+  /**
+   * 创建任务队列
+   */
+  private static createQueue(): JobQueue {
+    const queueType = process.env.QUEUE_TYPE || 'memory'
+
+    switch (queueType) {
+      case 'memory':
+        return this.createMemoryQueue()
+      
+      case 'database':
+        // TODO: 实现DatabaseQueue
+        console.warn('[JobFactory] DatabaseQueue not implemented yet, fallback to MemoryQueue')
+        return this.createMemoryQueue()
+      
+      default:
+        console.warn(`[JobFactory] Unknown QUEUE_TYPE: ${queueType}, fallback to memory`)
+        return this.createMemoryQueue()
+    }
+  }
+
+  /**
+   * 创建内存队列
+   */
+  private static createMemoryQueue(): MemoryQueue {
+    console.log('[JobFactory] Using MemoryQueue')
+    
+    const queue = new MemoryQueue()
+    
+    // 定期清理已完成的任务（避免内存泄漏）
+    if (process.env.NODE_ENV !== 'test') {
+      setInterval(() => {
+        queue.cleanup()
+      }, 60 * 60 * 1000) // 每小时清理一次
+    }
+    
+    return queue
+  }
+
+  /**
+   * 重置实例（用于测试）
+   */
+  static reset(): void {
+    this.instance = null
+  }
+}
+