Remove value now unused

No more API key and url needed because everything is managed by the backend.

Also backend does not accept a model parameter for the moment.

scribe/lib/scribe/ai/data/config/ai_config.dart

@@ -4,8 +4,4 @@ class AIConfig {
   const AIConfig._();
 
   static bool get isAiEnabled => dotenv.get('AI_ENABLED', fallback: 'false') == 'true';
-
-  static String get aiApiKey => dotenv.get('AI_API_KEY', fallback: '');
-
-  static String get aiApiUrl => dotenv.get('AI_API_URL', fallback: '');
 }

scribe/lib/scribe/ai/data/model/ai_api_request.dart

@@ -1,8 +1,6 @@
 import 'package:scribe/scribe/ai/data/model/ai_message.dart';
 
 class AIAPIRequest {
-  static const String _defaultModel = 'gpt-oss-120b';
-
   final List<AIMessage> messages;
 
   const AIAPIRequest({
@@ -11,7 +9,6 @@ class AIAPIRequest {
 
   Map<String, dynamic> toJson() {
     return {
-      'model': _defaultModel,
       'messages': messages.map((m) => m.toJson()).toList(),
     };
   }