19b7a9a473
RecommendedMaintenanceIntervalDays was a non-nullable int with [Range(1,3650)], so submitting the form without filling it in bound to 0 and failed validation. Made nullable on the entity, both DTOs, and the one controller callsite that calls .AddDays() (now uses .Value). Migration applied. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>