fix(backend): Resolve PgBoss infinite loop issue and cleanup unused files

Backend fixes:
- Fix PgBoss task infinite loop on SAE (root cause: missing queue table constraints)
- Add singletonKey to prevent duplicate job enqueueing
- Add idempotency check in reviewWorker (skip completed tasks)
- Add optimistic locking in reviewService (atomic status update)

Frontend fixes:
- Add isSubmitting state to prevent duplicate submissions in RVW Dashboard
- Fix API baseURL in knowledgeBaseApi (relative path)

Cleanup (removed):
- Old frontend/ directory (migrated to frontend-v2)
- python-microservice/ (unused, replaced by extraction_service)
- Root package.json and node_modules (accidentally created)
- redcap-docker-dev/ (external dependency)
- Various temporary files and outdated docs in root

New documentation:
- docs/07-运维文档/01-PgBoss队列监控与维护.md
- docs/07-运维文档/02-故障预防检查清单.md
- docs/07-运维文档/03-数据库迁移注意事项.md

Database fix applied to RDS:
- Added PRIMARY KEY to platform_schema.queue
- Added 3 missing foreign key constraints

Tested: Local build passed, RDS constraints verified

docs/03-业务模块/ASL-AI智能文献/02-技术设计/02-API设计规范.md

@@ -1360,25 +1360,13 @@ Body (raw JSON):
 **测试命令**:
 ```bash
 curl http://localhost:3001/api/v1/asl/projects/55941145-bba0-4b15-bda4-f0a398d78208/statistics
-```
-
----
-
-**文档版本：** v3.0  
+```---**文档版本：** v3.0  
 **最后更新：** 2025-11-23（Day 5: 全文复筛API）  
-**维护者：** AI智能文献开发团队
-
-**本次更新**：
+**维护者：** AI智能文献开发团队**本次更新**：
 - ✅ 新增全文复筛管理API（5个核心接口）
 - ✅ 详细的12字段评估文档
 - ✅ 双模型对比和冲突检测说明
 - ✅ Excel导出格式规范
-- ✅ 完整的请求/响应示例
-
----
-
-## 📚 相关文档
-
-- [数据库设计文档](./01-数据库设计.md)
+- ✅ 完整的请求/响应示例---## 📚 相关文档- [数据库设计文档](./01-数据库设计.md)
 - [API测试报告](../../../backend/ASL-API-测试报告.md)
 - [Week 1完成报告](../05-开发记录/2025-11-18-Week1完成报告.md)