Function check_cli 

pub async fn check_cli() -> Result<String, ClaudeError>

Checks that the claude CLI is available and returns its version string.

Runs claude --version and returns the trimmed stdout on success.

Errors

• ClaudeError::CliNotFound if claude is not in PATH.
• ClaudeError::NonZeroExit if the command fails.
• ClaudeError::Io for other I/O errors.