feat: Add Streamlit secrets support for OPENAI_API_KEY

Added fallback to load OPENAI_API_KEY from Streamlit secrets for
hosted deployments. Also added langchain-classic to requirements.txt.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: 2 people

examples/frontend/batch_speaker_app.py

@@ -33,6 +33,14 @@
 # Load environment variables once the module is imported
 load_dotenv(ENV_PATH)
 
+# Allow Streamlit secrets to provide API keys in hosted environments
+try:
+    secret_api_key = st.secrets.get("OPENAI_API_KEY")  # type: ignore[attr-defined]
+    if secret_api_key:
+        os.environ.setdefault("OPENAI_API_KEY", secret_api_key)
+except Exception:
+    pass
+
 
 class Speaker(BaseModel):
     """Schema for a single speaker entry."""

requirements.txt

@@ -3,4 +3,5 @@ myst-parser>=2.0.0
 sphinx-copybutton>=0.5.2
 sphinx-design>=0.5.0
 sphinx-autodoc-typehints>=1.25.2
-sphinx-autoapi>=3.0.0 
+sphinx-autoapi>=3.0.0
+langchain-classic>=0.1.0