feat(platform): Complete Postgres-Only architecture refactoring (Phase 1-7)

Major Changes:
- Implement Platform-Only architecture pattern (unified task management)
- Add PostgresCacheAdapter for unified caching (platform_schema.app_cache)
- Add PgBossQueue for job queue management (platform_schema.job)
- Implement CheckpointService using job.data (generic for all modules)
- Add intelligent threshold-based dual-mode processing (THRESHOLD=50)
- Add task splitting mechanism (auto chunk size recommendation)
- Refactor ASL screening service with smart mode selection
- Refactor DC extraction service with smart mode selection
- Register workers for ASL and DC modules

Technical Highlights:
- All task management data stored in platform_schema.job.data (JSONB)
- Business tables remain clean (no task management fields)
- CheckpointService is generic (shared by all modules)
- Zero code duplication (DRY principle)
- Follows 3-layer architecture principle
- Zero additional cost (no Redis needed, save 8400 CNY/year)

Code Statistics:
- New code: ~1750 lines
- Modified code: ~500 lines
- Test code: ~1800 lines
- Documentation: ~3000 lines

Testing:
- Unit tests: 8/8 passed
- Integration tests: 2/2 passed
- Architecture validation: passed
- Linter errors: 0

Files:
- Platform layer: PostgresCacheAdapter, PgBossQueue, CheckpointService, utils
- ASL module: screeningService, screeningWorker
- DC module: ExtractionController, extractionWorker
- Tests: 11 test files
- Docs: Updated 4 key documents

Status: Phase 1-7 completed, Phase 8-9 pending

backend/src/common/jobs/MemoryQueue.ts

@@ -36,6 +36,22 @@ export class MemoryQueue implements JobQueue {
   private handlers: Map<string, JobHandler> = new Map()
   private processing: boolean = false
 
+  /**
+   * 启动队列（MemoryQueue无需启动，立即可用）
+   */
+  async start(): Promise<void> {
+    // MemoryQueue不需要初始化，已经ready
+    this.processing = true
+  }
+
+  /**
+   * 停止队列（MemoryQueue无需清理）
+   */
+  async stop(): Promise<void> {
+    // MemoryQueue不需要清理
+    this.processing = false
+  }
+
   /**
    * 添加任务到队列
    */