Add EF Core support package, tests, docs update, and bump version to 1.1.0

[dombrovsky]

Summary

• add the StrongTypeIdGenerator.EntityFrameworkCore companion package for EF Core integration
• add EF Core integration tests covering scalar IDs, nullable IDs, CombinedId mapping, query translation, and registration edge cases
• add EF Core documentation and update package/version metadata for 1.1.0

Testing

• dotnet test

Closes #5