refactor: moved registries into a separate module and code cleanup

fix: refactored dial provider to follow the same pattern

providers/registries/__init__.py

@@ -0,0 +1,19 @@
+"""Registry implementations for provider capability manifests."""
+
+from .azure import AzureModelRegistry
+from .custom import CustomEndpointModelRegistry
+from .dial import DialModelRegistry
+from .gemini import GeminiModelRegistry
+from .openai import OpenAIModelRegistry
+from .openrouter import OpenRouterModelRegistry
+from .xai import XAIModelRegistry
+
+__all__ = [
+    "AzureModelRegistry",
+    "CustomEndpointModelRegistry",
+    "DialModelRegistry",
+    "GeminiModelRegistry",
+    "OpenAIModelRegistry",
+    "OpenRouterModelRegistry",
+    "XAIModelRegistry",
+]