Command line interface

TODO: this page will document every ostler-cli subcommand, its flags, exit codes, and a worked example. Cover the operator-level commands (install, status, logs, doctor, backup, restore) and the developer-level commands (re-index, rebuild wiki, rotate keys).

Owner: @andy. Cross-reference: the CLI source in CM051, and the PRODUCTISATION_CHECKLIST entries that gate which commands ship in the public binary versus stay developer-only.