feat: Refactor authentication and token management

- Updated EchoHubConnection to use ApiClient for token retrieval.
- Introduced ValidationConstants for common validation patterns and limits.
- Enhanced AuthDtos with refresh token support and expiration details.
- Added new ChatDtos for channel creation and topic updates.
- Created CommonDtos for error and paginated responses.
- Implemented RefreshToken model for managing refresh tokens.
- Modified JwtTokenService to generate and hash refresh tokens.
- Updated AuthController to handle registration, login, token refresh, and logout with improved error handling.
- Enhanced ChannelsController with channel creation, topic updates, and pagination for channel retrieval.
- Added FilesController for file management with rate limiting.
- Improved UsersController for profile updates and avatar uploads with validation.
- Integrated rate limiting across controllers to manage request load.
- Introduced FileValidationHelper for validating uploaded image files.
- Updated database context to include RefreshToken and enforce unique constraints.
- Enhanced ChatHub for improved channel and message handling with validation.
- Updated Program.cs to configure rate limiting and CORS policies.

src/EchoHub.Client/Services/EchoHubConnection.cs

@@ -19,14 +19,14 @@ public sealed class EchoHubConnection : IAsyncDisposable
 
     public bool IsConnected => _connection.State == HubConnectionState.Connected;
 
-    public EchoHubConnection(string serverUrl, string jwtToken)
+    public EchoHubConnection(string serverUrl, ApiClient apiClient)
     {
         var hubUrl = serverUrl.TrimEnd('/') + HubConstants.ChatHubPath;
 
         _connection = new HubConnectionBuilder()
             .WithUrl(hubUrl, options =>
             {
-                options.AccessTokenProvider = () => Task.FromResult<string?>(jwtToken);
+                options.AccessTokenProvider = () => apiClient.GetValidTokenAsync();
             })
             .WithAutomaticReconnect()
             .Build();