Convert Documents module to MediatR commands/queries

Replaces IDocumentService/DocumentService. The permission-check and
descendant-deletion logic moves to a shared DocumentAccess static
helper used by all seven handlers.

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

mws.application/Documents/Queries/GetDocument.cs

@@ -0,0 +1,16 @@
+using AutoMapper;
+using MediatR;
+using Mws.Application.Common;
+
+namespace Mws.Application.Documents;
+
+public record GetDocumentQuery(Guid UserId, Guid DocumentId) : IRequest<DocumentDto>;
+
+public class GetDocumentHandler(IUnitOfWork uow, IMapper mapper) : IRequestHandler<GetDocumentQuery, DocumentDto>
+{
+    public async Task<DocumentDto> Handle(GetDocumentQuery query, CancellationToken ct)
+    {
+        var doc = await DocumentAccess.GetDocumentForUserAsync(uow, query.UserId, query.DocumentId, ct);
+        return mapper.Map<DocumentDto>(doc);
+    }
+}

mws.application/Documents/Queries/GetDocumentTree.cs

@@ -0,0 +1,35 @@
+using AutoMapper;
+using MediatR;
+using Mws.Application.Common;
+using Mws.Application.Permissions;
+
+namespace Mws.Application.Documents;
+
+public record GetDocumentTreeQuery(Guid UserId, Guid ProjectId) : IRequest<List<DocumentNodeDto>>;
+
+public class GetDocumentTreeHandler(IUnitOfWork uow, IMapper mapper) : IRequestHandler<GetDocumentTreeQuery, List<DocumentNodeDto>>
+{
+    public async Task<List<DocumentNodeDto>> Handle(GetDocumentTreeQuery query, CancellationToken ct)
+    {
+        await DocumentAccess.EnsureDocumentPermissionAsync(uow, query.UserId, query.ProjectId, PermissionAction.View, ct);
+
+        var docs = await uow.Documents.GetTreeForProjectAsync(query.ProjectId, ct);
+
+        var nodes = docs.ToDictionary(d => d.Id, d => mapper.Map<DocumentNodeDto>(d));
+
+        var roots = new List<DocumentNodeDto>();
+        foreach (var node in nodes.Values)
+        {
+            if (node.ParentId is { } parentId && nodes.TryGetValue(parentId, out var parent))
+            {
+                parent.Children.Add(node);
+            }
+            else
+            {
+                roots.Add(node);
+            }
+        }
+
+        return roots;
+    }
+}

mws.application/Documents/Queries/SearchDocuments.cs

@@ -0,0 +1,17 @@
+using AutoMapper;
+using MediatR;
+using Mws.Application.Common;
+
+namespace Mws.Application.Documents;
+
+public record SearchDocumentsQuery(Guid UserId, string Term) : IRequest<List<DocumentNodeDto>>;
+
+public class SearchDocumentsHandler(IUnitOfWork uow, IMapper mapper) : IRequestHandler<SearchDocumentsQuery, List<DocumentNodeDto>>
+{
+    public async Task<List<DocumentNodeDto>> Handle(SearchDocumentsQuery query, CancellationToken ct)
+    {
+        var projectIds = await uow.Projects.GetDocumentViewableProjectIdsAsync(query.UserId, ct);
+        var results = await uow.Documents.SearchAsync(projectIds, query.Term, 20, ct);
+        return mapper.Map<List<DocumentNodeDto>>(results);
+    }
+}