Updated the domain layer to align with Clean Architecture principles:
- Removed Entity Framework dependencies from the project.
- Updated AGENTS.md to document the new architecture.
- Introduced repository interfaces for data access abstraction.
- Added a generic IRepository interface for CRUD operations.
- Implemented entity-specific repositories for Profile, ProfileSqlJob, and ProfileHistory.
- Ensured the domain layer is infrastructure-independent with pure POCOs.
- Updated project structure and documentation for clarity.
Introduced the `ECMJobRunner.Domain` project to support both
.NET Framework 4.8 and .NET 8.0. Added `Profile`,
`ProfileSqlJob`, and `ProfileHistory` entities to map to the
database schema, including relationships and audit fields.
Updated `ECMJobRunner.Domain.csproj` to enable multi-targeting
and added dependencies for Entity Framework 6.5.1 and EF Core
8.0.11. Enabled nullable reference types and set the language
version to `latest`.
Added comprehensive documentation in `AGENTS.md` detailing the
project structure, entities, database schema, and build
instructions.
