feat: Add NetworkMembershipCQ - Phase 4 Application Layer

- Implemented 3 Commands with handlers and validators:
  * JoinNetworkCommand: Add user to binary network tree
    - Validates parent exists and is in network
    - Validates leg position is empty
    - Records history with NetworkMembershipAction.Join
  * MoveInNetworkCommand: Move user to different position
    - Validates new parent and leg availability
    - Prevents circular dependencies (IsDescendant check)
    - Records old/new parent and leg in history
  * RemoveFromNetworkCommand: Remove user from network
    - Validates no children exist (must move/remove first)
    - Soft delete (sets NetworkParentId to null)
    - Idempotent design

- Implemented 3 Queries with handlers, validators, and DTOs:
  * GetNetworkTreeQuery: Binary tree visualization
    - Recursive tree building with MaxDepth limit (1-10)
    - Returns nested structure with Left/Right children
  * GetUserNetworkPositionQuery: User position details
    - Parent info, leg position, children counts
    - Left/Right child counts for balance view
  * GetNetworkMembershipHistoryQuery: Complete audit trail
    - Filter by UserId, pagination support
    - Shows Join/Move/Remove actions with full details

- All operations include complete history tracking
- Binary tree validation (parent-child relationships)
- Circular dependency prevention in MoveInNetwork
- 21 new files, ~850 lines of code
- Build successful with 0 errors

src/CMSMicroservice.Application/NetworkMembershipCQ/Queries/GetNetworkTree/GetNetworkTreeQuery.cs

@@ -0,0 +1,17 @@
+namespace CMSMicroservice.Application.NetworkMembershipCQ.Queries.GetNetworkTree;
+
+/// <summary>
+/// Query برای دریافت درخت شبکه از یک کاربر (Binary Tree)
+/// </summary>
+public record GetNetworkTreeQuery : IRequest<NetworkTreeDto?>
+{
+    /// <summary>
+    /// شناسه کاربر که می‌خواهیم درخت زیرمجموعه او را ببینیم
+    /// </summary>
+    public long UserId { get; init; }
+
+    /// <summary>
+    /// تعداد سطوح (Depth) که می‌خواهیم نمایش دهیم (پیش‌فرض: 3)
+    /// </summary>
+    public int MaxDepth { get; init; } = 3;
+}

src/CMSMicroservice.Application/NetworkMembershipCQ/Queries/GetNetworkTree/GetNetworkTreeQueryHandler.cs

@@ -0,0 +1,78 @@
+namespace CMSMicroservice.Application.NetworkMembershipCQ.Queries.GetNetworkTree;
+
+public class GetNetworkTreeQueryHandler : IRequestHandler<GetNetworkTreeQuery, NetworkTreeDto?>
+{
+    private readonly IApplicationDbContext _context;
+
+    public GetNetworkTreeQueryHandler(IApplicationDbContext context)
+    {
+        _context = context;
+    }
+
+    public async Task<NetworkTreeDto?> Handle(GetNetworkTreeQuery request, CancellationToken cancellationToken)
+    {
+        var rootUser = await _context.Users
+            .AsNoTracking()
+            .FirstOrDefaultAsync(x => x.Id == request.UserId, cancellationToken);
+
+        if (rootUser == null)
+        {
+            return null;
+        }
+
+        var tree = await BuildTree(rootUser.Id, request.MaxDepth, 0, cancellationToken);
+        return tree;
+    }
+
+    private async Task<NetworkTreeDto> BuildTree(long userId, int maxDepth, int currentDepth, CancellationToken cancellationToken)
+    {
+        var user = await _context.Users
+            .AsNoTracking()
+            .FirstOrDefaultAsync(x => x.Id == userId, cancellationToken);
+
+        if (user == null)
+        {
+            throw new NotFoundException(nameof(User), userId);
+        }
+
+        var node = new NetworkTreeDto
+        {
+            UserId = user.Id,
+            Mobile = user.Mobile,
+            FirstName = user.FirstName,
+            LastName = user.LastName,
+            LegPosition = user.LegPosition,
+            CurrentDepth = currentDepth
+        };
+
+        // اگر به حداکثر عمق رسیدیم، دیگر فرزندان را نمی‌خوانیم
+        if (currentDepth >= maxDepth)
+        {
+            return node;
+        }
+
+        // پیدا کردن فرزند چپ
+        var leftChild = await _context.Users
+            .AsNoTracking()
+            .FirstOrDefaultAsync(x => x.NetworkParentId == userId && x.LegPosition == NetworkLeg.Left,
+                cancellationToken);
+
+        if (leftChild != null)
+        {
+            node.LeftChild = await BuildTree(leftChild.Id, maxDepth, currentDepth + 1, cancellationToken);
+        }
+
+        // پیدا کردن فرزند راست
+        var rightChild = await _context.Users
+            .AsNoTracking()
+            .FirstOrDefaultAsync(x => x.NetworkParentId == userId && x.LegPosition == NetworkLeg.Right,
+                cancellationToken);
+
+        if (rightChild != null)
+        {
+            node.RightChild = await BuildTree(rightChild.Id, maxDepth, currentDepth + 1, cancellationToken);
+        }
+
+        return node;
+    }
+}

src/CMSMicroservice.Application/NetworkMembershipCQ/Queries/GetNetworkTree/GetNetworkTreeQueryValidator.cs

@@ -0,0 +1,28 @@
+namespace CMSMicroservice.Application.NetworkMembershipCQ.Queries.GetNetworkTree;
+
+public class GetNetworkTreeQueryValidator : AbstractValidator<GetNetworkTreeQuery>
+{
+    public GetNetworkTreeQueryValidator()
+    {
+        RuleFor(x => x.UserId)
+            .GreaterThan(0)
+            .WithMessage("شناسه کاربر معتبر نیست");
+
+        RuleFor(x => x.MaxDepth)
+            .InclusiveBetween(1, 10)
+            .WithMessage("عمق درخت باید بین 1 تا 10 باشد");
+    }
+
+    public Func<object, string, Task<IEnumerable<string>>> ValidateValue => async (model, propertyName) =>
+    {
+        var result = await ValidateAsync(
+            ValidationContext<GetNetworkTreeQuery>.CreateWithOptions(
+                (GetNetworkTreeQuery)model,
+                x => x.IncludeProperties(propertyName)));
+
+        if (result.IsValid)
+            return Array.Empty<string>();
+
+        return result.Errors.Select(e => e.ErrorMessage);
+    };
+}

src/CMSMicroservice.Application/NetworkMembershipCQ/Queries/GetNetworkTree/NetworkTreeDto.cs

@@ -0,0 +1,16 @@
+namespace CMSMicroservice.Application.NetworkMembershipCQ.Queries.GetNetworkTree;
+
+/// <summary>
+/// DTO برای نمایش درخت دوتایی شبکه
+/// </summary>
+public class NetworkTreeDto
+{
+    public long UserId { get; set; }
+    public string? Mobile { get; set; }
+    public string? FirstName { get; set; }
+    public string? LastName { get; set; }
+    public NetworkLeg? LegPosition { get; set; }
+    public int CurrentDepth { get; set; }
+    public NetworkTreeDto? LeftChild { get; set; }
+    public NetworkTreeDto? RightChild { get; set; }
+}