fix(runner): 保留同平台重试的并发租约

同平台 retry_same 之前会在首个 attempt 失败时释放任务级 admission 租约，下一次 attempt 继续续租旧租约并进入 upstream_submission_unknown。

现在明确区分 attempt 自有租约与任务级 admission 租约，只在 attempt 结束时释放前者；补充回归测试覆盖同平台重试继续续租 admission 租约。

验证：env -u AI_GATEWAY_TEST_DATABASE_URL go test ./... -count=1；go vet ./...；gofmt；git diff --check。

apps/api/internal/runner/execution_lease_test.go

@@ -31,3 +31,29 @@ func TestLeaseRenewalFatalityDistinguishesTransientDatabaseErrors(t *testing.T)
 		t.Fatal("concurrency lease renewal error at expiry must be fatal")
 	}
 }
+
+func TestBindAttemptConcurrencyLeasesPreservesAdmissionLeaseAcrossRetry(t *testing.T) {
+	attemptLease := store.ConcurrencyLease{ID: "attempt-lease", TTL: time.Minute}
+	admissionLeases := []store.ConcurrencyLease{
+		{ID: "admission-user-group", TTL: 2 * time.Minute},
+		{ID: "admission-worker-capacity", TTL: 2 * time.Minute},
+	}
+
+	active, release := bindAttemptConcurrencyLeases([]store.ConcurrencyLease{attemptLease}, admissionLeases)
+	if len(active) != 3 || active[0].ID != attemptLease.ID || active[1].ID != admissionLeases[0].ID || active[2].ID != admissionLeases[1].ID {
+		t.Fatalf("active leases must renew attempt and admission ownership together: %+v", active)
+	}
+	if len(release) != 1 || release[0].ID != attemptLease.ID {
+		t.Fatalf("attempt cleanup must not release task-scoped admission leases: %+v", release)
+	}
+
+	// A same-platform retry receives the same admission lease IDs. The first
+	// attempt cleanup must leave them renewable by the next attempt.
+	retryActive, retryRelease := bindAttemptConcurrencyLeases(nil, admissionLeases)
+	if len(retryActive) != 2 || retryActive[0].ID != admissionLeases[0].ID || retryActive[1].ID != admissionLeases[1].ID {
+		t.Fatalf("retry must keep using the live admission leases: %+v", retryActive)
+	}
+	if len(retryRelease) != 0 {
+		t.Fatalf("retry without attempt-owned leases must not release admission leases: %+v", retryRelease)
+	}
+}