Refactor: the project is now divided into a more clear structure, with **Infrastructure** and **Application** layers added.
Refactor: configurations are split into sections for different layers.
Fix: now EF Core related operations, such as migration, should be invoked in `OptixServe.Infrastructure`, with config file and data dir passed into `dotnet ef` command. See `OptixServe.Infrastructure/Utilites/DesignTimeDbContextFactory.cs` for details.
Fix: EF migrations are ignored in gitignore on purpose in early development.
Fix: re-implement `UserEndpoint` as static style which works best with minimal API, simplify the DI framework.
Fix: remove no needed service register in main program.
**Note: This implementation is not in minimalAPI way and not optimized, expected to be changed soon.**
Add: `UserService` and its interface `IUserService`.
Fix: `UserEndpoint` is now in instance class style with DI to work.
Fix: change main program to work with above design.