Implement LLM provider configuration and update user settings

- Added functionality to update the default LLM provider for users via a new endpoint in UserController.
- Introduced LlmProvider enum to manage available LLM options: Auto, Gemini, OpenAI, and Claude.
- Updated User and UserEntity models to include DefaultLlmProvider property.
- Enhanced database context and migrations to support the new LLM provider configuration.
- Integrated LLM services into the application bootstrap for dependency injection.
- Updated TypeScript API client to include methods for managing LLM providers and chat requests.

src/Managing.Domain/Users/User.cs

@@ -40,4 +40,7 @@ public class User
     [Id(17)] public decimal? SignalAgreementThreshold { get; set; }
     [Id(18)] public bool? AllowSignalTrendOverride { get; set; }
     [Id(19)] public TradingExchanges? DefaultExchange { get; set; }
+    
+    // User Settings - LLM Configuration
+    [Id(21)] public LlmProvider? DefaultLlmProvider { get; set; } = LlmProvider.Auto; // Default LLM provider
 }