Refactored Fake.cs to configure both in-memory and SQL Server
database contexts for testing, using the "Default" connection
string from configuration. Added detailed EF logging and SQL
executor setup. In TestBase.cs, fixed Setup to use the correct
repository instance for seeding email templates.
Changed test file namespaces from EnvelopeGenerator.Tests.Application to EnvelopeGenerator.Tests for consistency. Updated DigitalData.Core.Abstraction.Application package from 1.4.0 to 1.6.0 to incorporate latest improvements.