feat: add password protection for channels

- Updated IChatService to include password parameter in JoinChannelAsync method.
- Modified ChannelDto and related models to support password functionality.
- Implemented password handling in ChannelService for channel creation and membership validation.
- Enhanced IrcCommandHandler to manage channel join requests with passwords.
- Added ChannelPasswordDialog for user input when joining protected channels.
- Created database migration to add PasswordHash column to Channels table.
- Updated tests to cover new password functionality in channel joining and management.

src/EchoHub.Client/UI/Dialogs/ChannelPasswordDialog.cs

@@ -0,0 +1,72 @@
+using Terminal.Gui.App;
+using Terminal.Gui.ViewBase;
+using Terminal.Gui.Views;
+
+namespace EchoHub.Client.UI.Dialogs;
+
+/// <summary>
+/// Prompts for a channel password when joining a protected channel.
+/// Returns the entered password, or null if the user cancels.
+/// </summary>
+public sealed class ChannelPasswordDialog
+{
+    public static string? Show(IApplication app, string channelName, string? message = null)
+    {
+        string? result = null;
+
+        var dialog = new Dialog { Title = $"Join #{channelName}", Width = 50, Height = 10, CommandsToBubbleUp = [] };
+
+        var infoLabel = new Label
+        {
+            Text = message ?? $"#{channelName} is password protected.",
+            X = 1,
+            Y = 1
+        };
+
+        var passwordLabel = new Label { Text = "Password:", X = 1, Y = 3 };
+        var passwordField = new TextField { X = 11, Y = 3, Width = Dim.Fill(2), Secret = true };
+
+        var joinButton = new Button
+        {
+            Text = "Join",
+            IsDefault = true,
+            X = Pos.Center() - 9,
+            Y = 5
+        };
+
+        var cancelButton = new Button
+        {
+            Text = "Cancel",
+            X = Pos.Center() + 2,
+            Y = 5
+        };
+
+        joinButton.Accepting += (s, e) =>
+        {
+            var password = passwordField.Text;
+            if (string.IsNullOrEmpty(password))
+            {
+                MessageBox.ErrorQuery(app, "Error", "Password is required.", "OK");
+                return;
+            }
+
+            result = password;
+            e.Handled = true;
+            app.RequestStop();
+        };
+
+        cancelButton.Accepting += (s, e) =>
+        {
+            result = null;
+            e.Handled = true;
+            app.RequestStop();
+        };
+
+        dialog.Add(infoLabel, passwordLabel, passwordField, joinButton, cancelButton);
+
+        passwordField.SetFocus();
+        app.Run(dialog);
+
+        return result;
+    }
+}

src/EchoHub.Client/UI/Dialogs/CreateChannelDialog.cs

@@ -4,7 +4,7 @@ using Terminal.Gui.ViewBase;
 
 namespace EchoHub.Client.UI.Dialogs;
 
-public record CreateChannelResult(string Name, string? Topic, bool IsPublic);
+public record CreateChannelResult(string Name, string? Topic, bool IsPublic, string? Password);
 
 public sealed class CreateChannelDialog
 {
@@ -12,7 +12,7 @@ public sealed class CreateChannelDialog
     {
         CreateChannelResult? result = null;
 
-        var dialog = new Dialog { Title = "Create Channel", Width = 50, Height = 14, CommandsToBubbleUp = [] };
+        var dialog = new Dialog { Title = "Create Channel", Width = 50, Height = 16, CommandsToBubbleUp = [] };
 
         var nameLabel = new Label { Text = "Name:", X = 1, Y = 1 };
         var nameField = new TextField { X = 10, Y = 1, Width = Dim.Fill(2) };
@@ -20,19 +20,22 @@ public sealed class CreateChannelDialog
         var topicLabel = new Label { Text = "Topic:", X = 1, Y = 3 };
         var topicField = new TextField { X = 10, Y = 3, Width = Dim.Fill(2) };
 
+        var passwordLabel = new Label { Text = "Password:", X = 1, Y = 5 };
+        var passwordField = new TextField { X = 11, Y = 5, Width = Dim.Fill(2), Secret = true };
+
         var publicCheckbox = new CheckBox
         {
             Text = "Public (visible to all users)",
             X = 1,
-            Y = 5,
+            Y = 7,
             Value = CheckState.Checked
         };
 
         var hintLabel = new Label
         {
-            Text = "Lowercase letters, digits, hyphens, underscores (2-100 chars)",
+            Text = "Name: a-z, 0-9, -, _ (2-100 chars). Empty password = open channel.",
             X = 1,
-            Y = 7,
+            Y = 9,
         };
 
         var createButton = new Button
@@ -40,14 +43,14 @@ public sealed class CreateChannelDialog
             Text = "Create",
             IsDefault = true,
             X = Pos.Center() - 10,
-            Y = 9
+            Y = 11
         };
 
         var cancelButton = new Button
         {
             Text = "Cancel",
             X = Pos.Center() + 5,
-            Y = 9
+            Y = 11
         };
 
         createButton.Accepting += (s, e) =>
@@ -63,8 +66,12 @@ public sealed class CreateChannelDialog
             if (string.IsNullOrWhiteSpace(topic))
                 topic = null;
 
+            var password = passwordField.Text;
+            if (string.IsNullOrWhiteSpace(password))
+                password = null;
+
             var isPublic = publicCheckbox.Value == CheckState.Checked;
-            result = new CreateChannelResult(name, topic, isPublic);
+            result = new CreateChannelResult(name, topic, isPublic, password);
             e.Handled = true;
             app.RequestStop();
         };
@@ -76,7 +83,8 @@ public sealed class CreateChannelDialog
             app.RequestStop();
         };
 
-        dialog.Add(nameLabel, nameField, topicLabel, topicField, publicCheckbox, hintLabel, createButton, cancelButton);
+        dialog.Add(nameLabel, nameField, topicLabel, topicField, passwordLabel, passwordField,
+            publicCheckbox, hintLabel, createButton, cancelButton);
 
         nameField.SetFocus();
         app.Run(dialog);