Summary

• add .github/copilot-instructions.md with repo-specific build, test, architecture, and convention guidance for future Copilot sessions
• document the Database.cs execution flow, thin provider wrappers, SqlResult cursor model, and manual transaction commit behavior
• capture the current macOS SQLite test limitation so future sessions interpret local test failures correctly

Validation

• dotnet build --configuration Release
• dotnet test --configuration Release (fails on macOS because System.Data.SQLite.Core cannot load SQLite.Interop.dll)