Support .env files by default via dotenv/config #234
Description
Currently users need to manually configure dotenv to load environment variables from .env files when running evals.
Since loading env vars from .env files is an extremely common use case (API keys, config, etc.), we should support this by default.
Proposed solution:
Import dotenv/config automatically when running evals, so .env files are picked up without additional configuration.
Alternative:
Document how to configure dotenv loading, but this adds friction for a very standard use case.