release process for spec tests

[Andrew Kent (realark)]

• add a fetcher script that downloads a copy of the repo given a tag/sha
  • ./scripts/fetch.sh 0b74173 /target/dir (SDKs will use this in their build tools)
  • SDKs will integrate this into their build system
  • java example: https://github.com/braintrustdata/braintrust-sdk-java/blob/ark/spring-ai-revamp/btx/build.gradle#L83
• add a release script + workflow (for now, this just publishes a github release)
• add additional llm test cases

[Abhijeet Prasad (AbhiPrasad)]

nice this is awesome