feat: Add OPENAI_API_BASE environment variable support

pdfzh_translator.py

@@ -64,7 +64,7 @@ class OpenAITranslator(BaseTranslator):
         # Configure OpenAI client with environment variables
         self.client = openai.OpenAI(
             api_key=os.getenv('OPENAI_API_KEY'),
-            
+            base_url=os.getenv('OPENAI_API_BASE')
         )
 
     def translate(self, text) -> str: