Establish project-wide rules for testing (xUnit 3 / Shouldly / NSubstitute), logging (Microsoft.Extensions.Logging + Serilog + LogContext), and general C# conventions. Referenced from CLAUDE.md and phases 4-7.
Establish project-wide rules for testing (xUnit 3 / Shouldly / NSubstitute), logging (Microsoft.Extensions.Logging + Serilog + LogContext), and general C# conventions. Referenced from CLAUDE.md and phases 4-7.