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- Various temporary files and outdated docs in root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/08-项目管理/PKB和RVW功能迁移计划.md

@@ -190,7 +190,7 @@ DocumentUpload.tsx         // 文件上传（拖拽支持）
 - ✅ **双维度评估**：
   - 稿约规范性评估（11项标准）
   - 方法学评估（3大部分）
-- ✅ **基于真实期刊标准**：《中华脑血管病杂志》稿约
+- ✅ **基于真实期刊标准**：《中华医学超声杂志》稿约
 - ✅ **智能分析**：使用LLM进行结构化评估
 - ✅ **完整报告**：JSON格式结果，支持导出PDF/复制文本
 - ✅ **模型选择**：DeepSeek-V3 / Qwen3-72B / Qwen-Long
@@ -953,6 +953,8 @@ CREATE INDEX idx_rvw_tasks_created_at ON rvw_schema.review_tasks(created_at);
 
 
 
+
+