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/Services/EchoHubConnection.cs

@@ -16,6 +16,7 @@ public sealed class EchoHubConnection : IAsyncDisposable
     public event Action<UserPresenceDto>? OnUserStatusChanged;
     public event Action<string>? OnError;
     public event Action<string>? OnConnectionStateChanged;
+    public event Action? OnReconnected;
 
     public bool IsConnected => _connection.State == HubConnectionState.Connected;
 
@@ -42,6 +43,7 @@ public sealed class EchoHubConnection : IAsyncDisposable
         _connection.Reconnected += _ =>
         {
             OnConnectionStateChanged?.Invoke("Connected");
+            OnReconnected?.Invoke();
             return Task.CompletedTask;
         };