fix: decode paginated response in backup lifecycle integration test

`GET /api/v1/backups` now returns `{backups, total, limit, offset}` rather
than a flat array; update the test to decode the new envelope.

Author: Stan Misiurev

control-plane/internal/handlers/backup_integration_test.go

@@ -172,11 +172,13 @@ func TestIntegration_BackupLifecycle(t *testing.T) {
 		t.Fatalf("list all backups: expected 200, got %d", resp.StatusCode)
 		_ = body
 	}
-	var allBackups []map[string]interface{}
-	json.NewDecoder(resp.Body).Decode(&allBackups)
+	var allBackupsResp struct {
+		Backups []map[string]interface{} `json:"backups"`
+	}
+	json.NewDecoder(resp.Body).Decode(&allBackupsResp)
 	resp.Body.Close()
 	found := false
-	for _, b := range allBackups {
+	for _, b := range allBackupsResp.Backups {
 		if uint(b["id"].(float64)) == backupID {
 			found = true
 			break