Community tier auth, backup/restore, and test updates that were already
on this branch before the telemetry sprint. Includes updated telemetry
prompt test to match 3-option community tier flow.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Two-path authentication: enter 6-digit code in terminal OR click magic
link in email. Races both paths — whichever completes first wins.
Saves JWT to ~/.gstack/auth-token.json with auto-refresh. Includes
status and logout subcommands.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>