refactor: moved registries into a separate module and code cleanup

fix: refactored dial provider to follow the same pattern

tests/test_auto_mode_comprehensive.py

@@ -7,7 +7,7 @@ from unittest.mock import MagicMock, patch
 import pytest
 
 from providers.gemini import GeminiModelProvider
-from providers.openai_provider import OpenAIModelProvider
+from providers.openai import OpenAIModelProvider
 from providers.registry import ModelProviderRegistry
 from providers.shared import ProviderType
 from providers.xai import XAIModelProvider