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

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

@@ -0,0 +1,60 @@
+namespace VoiceCat.App.Forms;
+
+/// <summary>
+/// A small reusable modal that prompts for a single line of text (e.g., kick/ban reason).
+/// Returns DialogResult.OK with Text set, or DialogResult.Cancel.
+/// </summary>
+public sealed class InputDialog : Form
+{
+    private readonly TextBox _txtInput;
+
+    public string TextValue => _txtInput.Text.Trim();
+
+    public InputDialog(string caption, string label, string defaultText = "")
+    {
+        var lbl = new Label
+        {
+            Text = label,
+            AutoSize = true,
+            Location = new Point(12, 12),
+            TabIndex = 0,
+        };
+
+        _txtInput = new TextBox
+        {
+            Text = defaultText,
+            Location = new Point(12, 36),
+            Size = new Size(360, 23),
+            TabIndex = 1,
+        };
+
+        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;
+        AutoScaleMode = AutoScaleMode.Font;
+        ClientSize = new Size(384, 112);
+        Controls.AddRange([lbl, _txtInput, btnOk, btnCancel]);
+        FormBorderStyle = FormBorderStyle.FixedDialog;
+        MaximizeBox = false;
+        MinimizeBox = false;
+        StartPosition = FormStartPosition.CenterParent;
+        Text = caption;
+    }
+}