Document self-blocking prevention (excludeUserID), explicit reservation cancellation endpoint, background cleanup goroutine, and edit_request reservation scrubbing. Bump test counts from 1,169 to 1,180 and package count from 19 to 20. Add race detector command to README. Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent) Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>