Use "chat-model" as the name for llm-open-compatible

For example, after this change, the below provider gives
"deepseek-chat" instead of "Open AI" as the name.

```elisp
(make-llm-openai-compatible
  :url "https://api.deepseek.com/v1/"
  :chat-model "deepseek-chat"
  :key "...")
```

llm-openai.el

@@ -357,6 +357,11 @@ RESPONSE can be nil if the response is complete."
   "Return the name of the provider."
   "Open AI")
 
+(cl-defmethod llm-name ((provider llm-openai-compatible))
+  "Return the name of the `llm-openai-compatible' provider."
+  (or (llm-openai-compatible-chat-model provider)
+      "Open AI Compatible"))
+
 (cl-defmethod llm-chat-token-limit ((provider llm-openai))
   (llm-provider-utils-model-token-limit (llm-openai-chat-model provider)))