fix: ensure token usage recording, validate response model on stream

lib/crewai/tests/cassettes/test_gpt_4_1[gpt-4.1].yaml

@@ -1,7 +1,6 @@
 interactions:
 - request:
-    body: '{"messages": [{"role": "user", "content": "What is the capital of France?"}],
-      "model": "gpt-4.1", "stop": []}'
+    body: '{"messages": [{"role": "user", "content": "What is the capital of France?"}], "model": "gpt-4.1", "stop": []}'
     headers:
       accept:
       - application/json
@@ -41,22 +40,12 @@ interactions:
     uri: https://api.openai.com/v1/chat/completions
   response:
     body:
-      string: !!binary |
-        H4sIAAAAAAAAA4xSwYrbMBC9+yvEHEMcHMeh3dx2SwttoYTSW1nMRB7b2pUlIY27XZb8e5GdxM5u
-        C734MG/e83tP85IIAaqCnQDZIsvO6fRu//6Db26fnvTtx8/5t7v95rmT3y1+pc0XDcvIsIcHknxm
-        raTtnCZW1oyw9IRMUXX9rthu8pui2A5AZyvSkdY4TovVOs2zfJtmRbouTszWKkkBduJnIoQQL8M3
-        ejQV/YadyJbnSUchYEOwuywJAd7qOAEMQQVGw7CcQGkNkxls/2hJSHSKUQtbi08ejSShglgs9uhV
-        WCxWc6anug8YnZte6xmAxljGmHzwfH9CjheX2jbO20N4RYVaGRXa0hMGa6KjwNbBgB4TIe6HNvqr
-        gOC87RyXbB9p+N26GOVg6n8GnpoCtox6mudn0pVaWRGj0mHWJkiULVUTc6oe+0rZGZDMMr818zft
-        Mbcyzf/IT4CU5Jiq0nmqlLwOPK15itf5r7VLx4NhCOR/KUklK/LxHSqqsdfj3UB4DkxdWSvTkHde
-        jcdTuxJllh2yLMskJMfkDwAAAP//AwC4aq9JRgMAAA==
+      string: "{\n  \"id\": \"chatcmpl-BP8CrgAwwlAEI2NBP3ymcRoaKe3Jl\",\n  \"object\": \"chat.completion\",\n  \"created\": 1745329445,\n  \"model\": \"gpt-4.1-2025-04-14\",\n  \"choices\": [\n    {\n      \"index\": 0,\n      \"message\": {\n        \"role\": \"assistant\",\n        \"content\": \"The capital of France is **Paris**.\",\n        \"refusal\": null,\n        \"annotations\": []\n      },\n      \"logprobs\": null,\n      \"finish_reason\": \"stop\"\n    }\n  ],\n  \"usage\": {\n    \"prompt_tokens\": 14,\n    \"completion_tokens\": 10,\n    \"total_tokens\": 24,\n    \"prompt_tokens_details\": {\n      \"cached_tokens\": 0,\n      \"audio_tokens\": 0\n    },\n    \"completion_tokens_details\": {\n      \"reasoning_tokens\": 0,\n      \"audio_tokens\": 0,\n      \"accepted_prediction_tokens\": 0,\n      \"rejected_prediction_tokens\": 0\n    }\n  },\n  \"service_tier\": \"default\",\n  \"system_fingerprint\": \"fp_ac00b0000c\"\n}\n"
     headers:
       CF-RAY:
       - 93458dcc1b9df53b-GRU
       Connection:
       - keep-alive
-      Content-Encoding:
-      - gzip
       Content-Type:
       - application/json
       Date: