Add LLM configuration options and update deployment workflow

- Introduced new API keys for Anthropic and Google in .env.example and settings.py
- Updated llm.py to retrieve API keys directly from settings
- Modified deploy.yaml to streamline code checkout and improve deployment process

app/core/llm.py

@@ -26,9 +26,9 @@ from app.config.settings import settings
 def _api_key_for_model(model: str) -> str | None:
     """Return the most appropriate API key for the given LiteLLM model string."""
     if model.startswith("anthropic/"):
-        return getattr(settings, "ANTHROPIC_API_KEY", None) or None
+        return settings.ANTHROPIC_API_KEY or None
     if model.startswith("gemini/") or model.startswith("google/"):
-        return getattr(settings, "GOOGLE_API_KEY", None) or None
+        return settings.GOOGLE_API_KEY or None
     # Default: OpenAI-compatible (covers plain model names like "gpt-4o")
     return settings.OPENAI_API_KEY or None