Refactor repository pattern and modernize codebase

Removed `SaveChangesAsync` from `IRepository` and `Repository` to centralize transaction management in `DbContext`. Updated `CfgProfileRepository` to use `Context` property instead of `_context`. Refactored `Repository` class to use C# 9.0 record-like constructor syntax and replaced private fields with properties (`Context`, `DbSet`, `Mapper`).

Replaced `Any()` with `Count == 0` for null checks and updated `FindAsync` to use C# 11 object array syntax. Added conditional compilation for framework-specific differences. These changes improve readability, consistency, and leverage modern C# features.

ECMJobRunner.Domain/Interfaces/IRepository.cs

@@ -90,10 +90,5 @@ namespace ECMJobRunner.Domain.Interfaces
         /// <param name="cancellationToken">Cancellation token</param>
         /// <returns>True if entity was found and deleted, false otherwise</returns>
         Task<bool> DeleteSingleAsync(Expression<Func<TEntity, bool>> predicate, CancellationToken cancellationToken = default);
-
-        /// <summary>
-        /// Save all changes asynchronously
-        /// </summary>
-        Task<int> SaveChangesAsync(CancellationToken cancellationToken = default);
     }
 }