Workers, release commands & cron

Process groups: [processes] in aloof.toml. web receives HTTP. Each other group runs as a worker app <app>-<group> with the same image, env and networks, no health probe and no sleeping. Scale a group with aloof scale count worker=3, and resize it with aloof scale vm perf-2x-4gb --group worker.

Release command: [deploy] release_command runs once after the build, before any new instance starts, in a one-off machine with the same image, env, private networks and volumes. If it exits non-zero, the release fails and the previous release keeps serving.

Cron / scheduled machines: [[cron]] jobs run on schedule (UTC, 5-field or @daily) as one-off machines from the current release. The exit code and output of the last 50 runs of each job are kept: aloof cron list, aloof cron run nightly.

Preview deploys: per PR through the GitHub App, or aloof previews create <n> <ref> for any git host.