fix(acceptance): 隔离控制面抖动与租约瞬态故障

线上 P24 验收暴露出高频 kubectl exec 放大 K3s API 压力、门禁查询挤占关键连接池，以及 PostgreSQL 锁超时被误判为租约所有权丢失。

本次合并验收身份查询、在租约有效期内重试瞬态续期错误、修复人工审核残留 attempt，并增加滚动后 etcd 稳定窗口、节点直连指标和双站独立报告。

验证：Go 全量测试、go vet、聚焦 race、gofmt、迁移安全检查、bash -n、ShellCheck、manual release test。

apps/api/internal/runner/execution_lease_test.go

@@ -0,0 +1,33 @@
+package runner
+
+import (
+	"errors"
+	"testing"
+	"time"
+
+	"github.com/easyai/easyai-ai-gateway/apps/api/internal/store"
+)
+
+func TestLeaseRenewalFatalityDistinguishesTransientDatabaseErrors(t *testing.T) {
+	now := time.Now()
+	deadline := now.Add(time.Minute)
+	transient := errors.New("lock timeout")
+	if taskExecutionLeaseRenewalIsFatal(transient, now, deadline) {
+		t.Fatal("transient task lease renewal error must be retried before expiry")
+	}
+	if concurrencyLeaseRenewalIsFatal(transient, now, deadline) {
+		t.Fatal("transient concurrency lease renewal error must be retried before expiry")
+	}
+	if !taskExecutionLeaseRenewalIsFatal(store.ErrTaskExecutionLeaseLost, now, deadline) {
+		t.Fatal("confirmed task lease ownership loss must be fatal")
+	}
+	if !concurrencyLeaseRenewalIsFatal(store.ErrConcurrencyLeaseLost, now, deadline) {
+		t.Fatal("confirmed concurrency lease ownership loss must be fatal")
+	}
+	if !taskExecutionLeaseRenewalIsFatal(transient, deadline, deadline) {
+		t.Fatal("task lease renewal error at expiry must be fatal")
+	}
+	if !concurrencyLeaseRenewalIsFatal(transient, deadline, deadline) {
+		t.Fatal("concurrency lease renewal error at expiry must be fatal")
+	}
+}