Docker Desktop stays dead after disk-full: kill the stale backend

After macOS ran out of disk, Docker Desktop hung (docker info never returned). Quitting the app with osascript and running open -a Docker did not bring it back: a stale com.docker.backend process from the frozen session kept running, the socket file stayed in place, and every client got 'Cannot connect to the Docker daemon' indefinitely. Killing that leftover com.docker.backend PID (kill, then kill -9 if needed) and running open -a Docker again brought the daemon up in about 10 seconds. Check with pgrep -fl com.docker before relaunching.