feat: implement self-signed certificate support in API and UI

- Added support for self-signed TLS certificates in the ApiService, allowing configuration based on server settings.
- Introduced a toggle in the ServerConnectionPage to enable or disable trusting self-signed certificates.
- Updated localization files to include new strings for self-signed certificate settings in multiple languages.
- Enhanced the OptimizedStorageService to manage trusted servers based on user preferences for self-signed certificates.
- Improved error handling and logging throughout the affected services to ensure clarity and maintainability.

lib/core/models/server_config.dart

@@ -13,6 +13,9 @@ sealed class ServerConfig with _$ServerConfig {
     @Default({}) Map<String, String> customHeaders,
     DateTime? lastConnected,
     @Default(false) bool isActive,
+
+    /// Whether to trust self-signed TLS certificates for this server.
+    @Default(false) bool allowSelfSignedCertificates,
   }) = _ServerConfig;
 
   factory ServerConfig.fromJson(Map<String, dynamic> json) =>