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/tests/verify-test1-database.sql

@@ -0,0 +1,85 @@
+-- ============================================
+-- 验证测试1的数据库状态
+-- ============================================
+
+\echo '=========================================='
+\echo '1. 检查 app_cache 表是否存在'
+\echo '=========================================='
+\dt platform_schema.app_cache
+
+\echo ''
+\echo '=========================================='
+\echo '2. 查看表结构'
+\echo '=========================================='
+\d platform_schema.app_cache
+
+\echo ''
+\echo '=========================================='
+\echo '3. 查看索引'
+\echo '=========================================='
+SELECT indexname, indexdef 
+FROM pg_indexes 
+WHERE schemaname = 'platform_schema' 
+  AND tablename = 'app_cache';
+
+\echo ''
+\echo '=========================================='
+\echo '4. 检查测试数据是否清理（应为0行）'
+\echo '=========================================='
+SELECT COUNT(*) as test_data_count 
+FROM platform_schema.app_cache 
+WHERE key LIKE 'test:%';
+
+\echo ''
+\echo '=========================================='
+\echo '5. 查看所有缓存数据'
+\echo '=========================================='
+SELECT id, key, 
+       LEFT(value::text, 50) as value_preview, 
+       expires_at, 
+       created_at 
+FROM platform_schema.app_cache 
+ORDER BY created_at DESC 
+LIMIT 10;
+
+\echo ''
+\echo '=========================================='
+\echo '6. 查看表统计信息'
+\echo '=========================================='
+SELECT 
+  COUNT(*) as total_records,
+  pg_size_pretty(pg_total_relation_size('platform_schema.app_cache')) as total_size,
+  pg_size_pretty(pg_relation_size('platform_schema.app_cache')) as table_size,
+  pg_size_pretty(pg_indexes_size('platform_schema.app_cache')) as indexes_size
+FROM platform_schema.app_cache;
+
+\echo ''
+\echo '=========================================='
+\echo '7. 测试写入和删除（不会影响现有数据）'
+\echo '=========================================='
+
+-- 插入测试数据
+INSERT INTO platform_schema.app_cache (key, value, expires_at, created_at)
+VALUES ('verify_test', '{"status": "ok"}', NOW() + INTERVAL '1 hour', NOW());
+
+-- 验证插入
+SELECT 'INSERT 成功' as result 
+FROM platform_schema.app_cache 
+WHERE key = 'verify_test';
+
+-- 删除测试数据
+DELETE FROM platform_schema.app_cache WHERE key = 'verify_test';
+
+-- 验证删除
+SELECT CASE 
+  WHEN COUNT(*) = 0 THEN 'DELETE 成功' 
+  ELSE 'DELETE 失败' 
+END as result
+FROM platform_schema.app_cache 
+WHERE key = 'verify_test';
+
+\echo ''
+\echo '=========================================='
+\echo '✅ 数据库验证完成！'
+\echo '=========================================='
+