fix(queue): 防止过期执行占位阻塞与重复提交

队列恢复后，仍在运行标记中的 River job 可能保留 waiting admission，形成全局 FIFO 队头阻塞；同时旧执行在租约被接管后仍可能创建 attempt 或切换到 submitting。

新增 stale admission 自动让出机制，并用当前 execution token 对 attempt 创建和上游提交状态切换做 fencing。任务、River job 和结算状态均不在让出流程中改写。

验证：go vet ./...；env -u AI_GATEWAY_TEST_DATABASE_URL go test ./... -count=1；真实 PostgreSQL 集成测试覆盖 stale admission 让出与旧 token 提交拦截。

apps/api/internal/runner/service.go

@@ -1206,6 +1206,7 @@ func (s *Service) runCandidate(
 
 	attemptID, err := s.store.CreateTaskAttempt(ctx, store.CreateTaskAttemptInput{
 		TaskID:             task.ID,
+		ExecutionToken:     task.ExecutionToken,
 		AttemptNo:          attemptNo,
 		PlatformID:         candidate.PlatformID,
 		PlatformModelID:    candidate.PlatformModelID,
@@ -1334,7 +1335,13 @@ func (s *Service) runCandidate(
 	if strings.TrimSpace(task.RemoteTaskID) != "" {
 		submissionStatus = "response_received"
 		markUpstreamSubmissionStarted(ctx)
-		if err := s.store.SetAttemptUpstreamSubmissionStatus(ctx, attemptID, submissionStatus); err != nil {
+		if err := s.store.SetAttemptUpstreamSubmissionStatusForExecution(
+			ctx,
+			attemptID,
+			task.ID,
+			task.ExecutionToken,
+			submissionStatus,
+		); err != nil {
 			return clients.Response{}, fmt.Errorf("restore upstream submission status: %w", err)
 		}
 	}
@@ -1345,7 +1352,13 @@ func (s *Service) runCandidate(
 		if submissionStatus == status {
 			return nil
 		}
-		if err := s.store.SetAttemptUpstreamSubmissionStatus(context.WithoutCancel(ctx), attemptID, status); err != nil {
+		if err := s.store.SetAttemptUpstreamSubmissionStatusForExecution(
+			context.WithoutCancel(ctx),
+			attemptID,
+			task.ID,
+			task.ExecutionToken,
+			status,
+		); err != nil {
 			return err
 		}
 		submissionStatus = status
@@ -1883,6 +1896,7 @@ func (s *Service) recordFailedAttempt(ctx context.Context, input failedAttemptRe
 	metrics := mergeMetrics(append([]map[string]any{baseMetrics, failure}, input.ExtraMetrics...)...)
 	attemptID, err := s.store.CreateTaskAttempt(ctx, store.CreateTaskAttemptInput{
 		TaskID:          input.Task.ID,
+		ExecutionToken:  input.Task.ExecutionToken,
 		AttemptNo:       attemptNo,
 		PlatformID:      platformID,
 		PlatformModelID: platformModelID,