- Added System.Text.Json.Serialization namespace and [JsonIgnore] attributes to Top and Left properties in Signature entity for .NET builds
- Applied null-forgiving operator (!) and null-coalescing defaults for frame.X and frame.Y in BurnPdfCommandHandler
- Improved runtime safety and prevented unintended JSON serialization of computed properties
- Introduced conditional EF Core configuration to support InMemoryDatabase for testing or lightweight runs.
- Added `UseInMemoryDb` config flag read from appsettings.
- Retained SQL Server as the default when the flag is false.
- Added missing Quartz namespace import.