build: load OPENAI_API_KEY from .env using python-dotenv in batch_o3_prompts.py

Co-authored-by: aider (o3) <aider@aider.chat>

requirements.txt

@@ -1 +1,2 @@
 openai>=1.0.0
+python-dotenv>=1.0.0

scripts/batch_o3_prompts.py

@@ -19,6 +19,7 @@ import sys
 from pathlib import Path
 from typing import Any, Dict
 
+from dotenv import load_dotenv
 import openai
 
 MODEL = "o3"
@@ -53,6 +54,7 @@ def call_o3(prompt: str) -> str:
 
 def main(argv: list[str] | None = None) -> None:
     argv = argv or sys.argv[1:]
+    load_dotenv()  # read variables from .env if present
     if len(argv) != 3:
         print(main.__doc__)
         sys.exit(1)