feat: Add Create Channel dialog and related events

- Introduced CreateChannelDialog for user to create new channels with name and topic.
- Added OnCreateChannelRequested event in MainWindow for channel creation.
- Enhanced EchoHubConnection with OnReconnected event for connection state handling.
- Updated EchoHubDbContext to use application base directory for SQLite database path.
- Integrated Serilog for logging in EchoHub.Server.
- Refactored database initialization and migration logic into DatabaseSetup class.
- Implemented FirstRunSetup to ensure appsettings.json and generate JWT secret if needed.
- Updated appsettings files to configure Serilog logging.
- Enhanced error handling and logging in ChatHub methods for better traceability.

src/EchoHub.Client/AsyncRunner.cs

@@ -0,0 +1,32 @@
+using Serilog;
+using Terminal.Gui.App;
+
+namespace EchoHub.Client;
+
+/// <summary>
+/// Eliminates repeated Task.Run/try/catch/app.Invoke(ShowError) boilerplate.
+/// Runs async work on a background thread and routes exceptions to the UI.
+/// </summary>
+public static class AsyncRunner
+{
+    public static void Run(
+        IApplication app,
+        Func<Task> work,
+        Action<string> showError,
+        string errorPrefix,
+        string? logContext = null)
+    {
+        Task.Run(async () =>
+        {
+            try
+            {
+                await work();
+            }
+            catch (Exception ex)
+            {
+                Log.Error(ex, "{Context} failed", logContext ?? errorPrefix);
+                app.Invoke(() => showError($"{errorPrefix}: {ex.Message}"));
+            }
+        });
+    }
+}