refactor: move database-related projects to separate folder

SqlData/Application/Cqrs/Discipline/Queries/GetDisciplineList/DisciplineListVm.cs

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+using System.Collections.Generic;
+
+namespace Mirea.Api.DataAccess.Application.Cqrs.Discipline.Queries.GetDisciplineList;
+
+/// <summary>
+/// Represents a view model containing multiple disciplines name.
+/// </summary>
+public class DisciplineListVm
+{
+    /// <summary>
+    /// The list of disciplines.
+    /// </summary>
+    public IList<DisciplineLookupDto> Disciplines { get; set; } = new List<DisciplineLookupDto>();
+}

SqlData/Application/Cqrs/Discipline/Queries/GetDisciplineList/DisciplineLookupDto.cs

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+namespace Mirea.Api.DataAccess.Application.Cqrs.Discipline.Queries.GetDisciplineList;
+
+/// <summary>
+/// Represents disciplines.
+/// </summary>
+public class DisciplineLookupDto
+{
+    /// <summary>
+    /// The unique identifier for the discipline.
+    /// </summary>
+    public int Id { get; set; }
+
+    /// <summary>
+    /// The name of the discipline.
+    /// </summary>
+    public required string Name { get; set; }
+}

SqlData/Application/Cqrs/Discipline/Queries/GetDisciplineList/GetDisciplineListQuery.cs

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+using MediatR;
+
+namespace Mirea.Api.DataAccess.Application.Cqrs.Discipline.Queries.GetDisciplineList;
+
+public class GetDisciplineListQuery : IRequest<DisciplineListVm>
+{
+    public int? Page { get; set; }
+    public int? PageSize { get; set; }
+}

SqlData/Application/Cqrs/Discipline/Queries/GetDisciplineList/GetDisciplineListQueryHandler.cs

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+using MediatR;
+using Microsoft.EntityFrameworkCore;
+using Mirea.Api.DataAccess.Application.Interfaces.DbContexts.Schedule;
+using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace Mirea.Api.DataAccess.Application.Cqrs.Discipline.Queries.GetDisciplineList;
+
+public class GetDisciplineListQueryHandler(IDisciplineDbContext dbContext) : IRequestHandler<GetDisciplineListQuery, DisciplineListVm>
+{
+    public async Task<DisciplineListVm> Handle(GetDisciplineListQuery request, CancellationToken cancellationToken)
+    {
+        var dtos = dbContext.Disciplines.OrderBy(d => d.Id).Select(d => new DisciplineLookupDto()
+        {
+            Id = d.Id,
+            Name = d.Name,
+        });
+
+        if (request is { PageSize: not null, Page: not null })
+            dtos = dtos.Skip(request.Page.Value * request.PageSize.Value).Take(request.PageSize.Value);
+
+        var result = await dtos.ToListAsync(cancellationToken);
+
+        return new DisciplineListVm
+        {
+            Disciplines = result
+        };
+    }
+}