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/index.ts

@@ -15,6 +15,9 @@ import { registerDCRoutes, initDCModule } from './modules/dc/index.js';
 import { registerHealthRoutes } from './common/health/index.js';
 import { logger } from './common/logging/index.js';
 import { registerTestRoutes } from './test-platform-api.js';
+import { registerScreeningWorkers } from './modules/asl/services/screeningWorker.js';
+import { registerExtractionWorkers } from './modules/dc/tool-b/workers/extractionWorker.js';
+import { jobQueue } from './common/jobs/index.js';
 
 
 // 全局处理BigInt序列化
@@ -127,6 +130,38 @@ const start = async () => {
       process.exit(1);
     }
     
+    // ============================================
+    // 【Postgres-Only】启动队列和注册Workers
+    // ============================================
+    try {
+      logger.info('🚀 Starting Postgres-Only queue and workers...');
+      
+      // 启动队列（pg-boss）
+      await jobQueue.start();
+      logger.info('✅ Queue started (pg-boss)');
+      
+      // 注册ASL筛选Workers
+      registerScreeningWorkers();
+      logger.info('✅ ASL screening workers registered');
+      
+      // 注册DC提取Workers
+      registerExtractionWorkers();
+      logger.info('✅ DC extraction workers registered');
+      
+      console.log('\n' + '='.repeat(60));
+      console.log('✅ Postgres-Only 架构已启动');
+      console.log('='.repeat(60));
+      console.log('📦 队列类型: pg-boss');
+      console.log('📦 缓存类型: PostgreSQL');
+      console.log('📦 注册的Workers:');
+      console.log('   - asl:screening:batch (文献筛选批次处理)');
+      console.log('='.repeat(60) + '\n');
+    } catch (error) {
+      logger.error('❌ Failed to start Postgres-Only architecture', { error });
+      console.error('❌ Postgres-Only 架构启动失败:', error);
+      process.exit(1);
+    }
+    
     // 初始化DC模块（Seed预设模板）
     try {
       await initDCModule();