Worker now runs `claude --version` before listening; on non-zero exit
it logs critical and exits with code 1. Skippable via env var
CLAUDEDO_SKIP_CLI_PREFLIGHT=1 for environments without the CLI (tests,
dev). Closes verification step 2 / open.md item 3.1.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
