[feat] enhance model pricing registration to merge with existing pricing details

Author: Mounir-charef

edenai_apis/llmengine/clients/litellm_client/litellm_client.py

@@ -864,7 +864,11 @@ async def acompletion(
             kwargs.pop("moderate_content", None)
             # Register custom model pricing in litellm's registry for extended pricing support
             if model_pricing:
-                litellm.model_cost[model_name] = model_pricing
+                # Merge with existing pricing to preserve other fields (max_tokens, mode, etc.)
+                if model_name in litellm.model_cost:
+                    litellm.model_cost[model_name].update(model_pricing)
+                else:
+                    litellm.model_cost[model_name] = model_pricing
             provider_start_time = time.time_ns()
             c_response = await acompletion(**call_params, **kwargs)
             provider_end_time = time.time_ns()