M5: Windows client moderation UI; add C ABI getters for account list, user mute/deafen, channel topic

clients/windows/VoiceCat.App/Forms/MoveUserDialog.cs

@@ -0,0 +1,79 @@
+using VoiceCat.Interop;
+
+namespace VoiceCat.App.Forms;
+
+/// <summary>
+/// Prompt the moderator to pick a destination channel for a user move.
+/// </summary>
+public sealed class MoveUserDialog : Form
+{
+    private readonly ComboBox _cboChannel;
+
+    public uint SelectedChannelId { get; private set; }
+
+    public MoveUserDialog(IEnumerable<ChannelInfo> channels, uint currentChannelId)
+    {
+        Text = "Move user to channel";
+        FormBorderStyle = FormBorderStyle.FixedDialog;
+        MaximizeBox = false;
+        MinimizeBox = false;
+        StartPosition = FormStartPosition.CenterParent;
+        AutoScaleMode = AutoScaleMode.Font;
+        ClientSize = new Size(384, 120);
+
+        var lbl = new Label
+        {
+            Text = "&Destination channel:",
+            Location = new Point(12, 12),
+            AutoSize = true,
+        };
+
+        _cboChannel = new ComboBox
+        {
+            Location = new Point(12, 36),
+            Size = new Size(360, 23),
+            DropDownStyle = ComboBoxStyle.DropDownList,
+            TabIndex = 1,
+        };
+
+        foreach (var ch in channels.OrderBy(c => c.Name))
+        {
+            _cboChannel.Items.Add(new ChannelItem(ch.Name, ch.Id));
+            if (ch.Id == currentChannelId) _cboChannel.SelectedIndex = _cboChannel.Items.Count - 1;
+        }
+        if (_cboChannel.SelectedIndex < 0 && _cboChannel.Items.Count > 0)
+            _cboChannel.SelectedIndex = 0;
+
+        var btnOk = new Button
+        {
+            Text = "&OK",
+            DialogResult = DialogResult.OK,
+            Location = new Point(216, 72),
+            Size = new Size(75, 27),
+            TabIndex = 2,
+        };
+        var btnCancel = new Button
+        {
+            Text = "&Cancel",
+            DialogResult = DialogResult.Cancel,
+            Location = new Point(297, 72),
+            Size = new Size(75, 27),
+            TabIndex = 3,
+        };
+
+        AcceptButton = btnOk;
+        CancelButton = btnCancel;
+        Controls.AddRange([lbl, _cboChannel, btnOk, btnCancel]);
+
+        btnOk.Click += (_, _) =>
+        {
+            SelectedChannelId = (_cboChannel.SelectedItem as ChannelItem)?.Id ?? 0;
+        };
+    }
+
+    private sealed class ChannelItem(string name, uint id)
+    {
+        public uint Id { get; } = id;
+        public override string ToString() => name;
+    }
+}