frontend-backend-rules-maintainer

Maintain and enforce front-end/back-end collaboration constraints. Triggered when users request defining or adjusting API contracts, error-code mappings, integration workflows, release ordering, and rollback strategies. Especially applicable to scenarios that require joint cross-end consistency audits with `rules/frontend`, `rules/go-server`, `rules/dotnet-server`, and `rules/frontend-backend-collaboration.md`, and that must produce mergeable conclusions (including P0/P1 risk levels).