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- Various temporary files and outdated docs in root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

backend/src/modules/rvw/services/reviewService.ts

@@ -156,9 +156,14 @@ export async function runReview(params: RunReviewParams): Promise<{ jobId: strin
     throw new Error('文档尚未提取完成，请稍后再试');
   }
 
-  // 更新任务状态为reviewing
-  await prisma.reviewTask.update({
-    where: { id: taskId },
+  // 🔒 使用原子操作实现幂等性（防止并发请求重复入队）
+  // updateMany 只会更新匹配条件的记录，返回更新数量
+  const updateResult = await prisma.reviewTask.updateMany({
+    where: { 
+      id: taskId,
+      // 只有当状态是 pending/completed/failed 时才允许启动
+      status: { in: ['pending', 'completed', 'failed'] }
+    },
     data: {
       status: 'reviewing',
       selectedAgents: agents,
@@ -171,6 +176,14 @@ export async function runReview(params: RunReviewParams): Promise<{ jobId: strin
     },
   });
 
+  // 🔒 幂等性检查：如果没有更新任何记录，说明任务已经在运行中
+  if (updateResult.count === 0) {
+    logger.warn('[RVW] ⚠️ 任务已在运行中，拒绝重复启动', { taskId, currentStatus: task.status });
+    throw new Error('任务已在运行中，请勿重复提交');
+  }
+
+  logger.info('[RVW] ✅ 任务状态已原子更新为 reviewing', { taskId });
+
   // ✅ 推送任务到 pg-boss 队列（Platform-Only架构）
   const job = await jobQueue.push('rvw_review_task', {
     taskId,

backend/src/modules/rvw/workers/reviewWorker.ts

@@ -63,6 +63,29 @@ export function registerReviewWorker() {
     console.log(`  文本长度: ${extractedText.length} 字符`);
 
     try {
+      // ✅ 检查任务是否已经完成（防止重复处理）
+      const existingTask = await prisma.reviewTask.findUnique({
+        where: { id: taskId },
+        select: { status: true, completedAt: true, overallScore: true },
+      });
+
+      if (existingTask?.status === 'completed' && existingTask.completedAt) {
+        logger.warn('[reviewWorker] ⚠️ Task already completed, skipping', {
+          jobId: job.id,
+          taskId,
+          completedAt: existingTask.completedAt,
+          overallScore: existingTask.overallScore,
+        });
+        console.log(`\n⚠️ 任务已完成，跳过重复处理`);
+        console.log(`  Task ID: ${taskId}`);
+        console.log(`  完成时间: ${existingTask.completedAt}`);
+        console.log(`  得分: ${existingTask.overallScore}`);
+        return {
+          taskId,
+          skipped: true,
+          reason: 'Task already completed',
+        };
+      }
       // ========================================
       // 1. 运行选中的智能体
       // ========================================