Convert Projects module to MediatR commands/queries

Replaces IProjectService/ProjectService. IProjectMemberService is
left in place for now — ProjectMembersController still depends on it
until the next task converts it too.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

mws.application/Projects/Queries/GetProjects.cs

@@ -0,0 +1,16 @@
+using AutoMapper;
+using MediatR;
+using Mws.Application.Common;
+
+namespace Mws.Application.Projects;
+
+public record GetProjectsQuery(Guid UserId) : IRequest<List<ProjectDto>>;
+
+public class GetProjectsHandler(IUnitOfWork uow, IMapper mapper) : IRequestHandler<GetProjectsQuery, List<ProjectDto>>
+{
+    public async Task<List<ProjectDto>> Handle(GetProjectsQuery query, CancellationToken ct)
+    {
+        var projects = await uow.Projects.GetForUserAsync(query.UserId, ct);
+        return mapper.Map<List<ProjectDto>>(projects);
+    }
+}