- Update all LLM model files to use getSecretSync with AI_KEYS constants
- Migrate OpenAI GPT models (gpt-5, gpt-5-mini, gpt-5-nano) to use secrets system
- Migrate Anthropic models (sonnet-4, haiku-3-5) to use secrets for both Anthropic API and Vertex AI credentials
- Update provider files (openai.ts, anthropic.ts, vertex.ts) to use getSecretSync
- Migrate evaluation workflow to use BRAINTRUST_KEY from secrets
- Implement proper error handling for missing credentials with try-catch blocks
- Test files will be migrated in a separate update
All non-test source files now use centralized secrets management instead of direct process.env access.