chore: ignore local runtime snapshots under backups/

backups/catalog-integrity/pre-fix.json is a one-off database snapshot taken
during an incident, not source. Kept on disk for reference, out of git.

.gitignore

@@ -54,3 +54,7 @@ blob-report/
 .env.install.*
 build-reports/
 !/docs/performance-budgets.md
+
+# One-off local snapshots (o.a. catalog-integrity/pre-fix.json): runtime-werk,
+# geen bron. Per map opgeslagen om een incident terug te kunnen lezen.
+backups/