Restore the Vault kv/CICD/AI_WORKSPACE_AUTH_TOKEN read in the deploy job
(the key now exists) and resolve the bootstrap token with a clear
precedence: workflow_dispatch input overrides, else Vault value, else
the on-host installer's resolve_unified_auth_token reuses the persisted
~/.ai_workspace_auth_token or generates a new one.
Also fix run-on-host-bootstrap.sh which silently dropped
AI_WORKSPACE_AUTH_TOKEN: it is now written to the remote env payload and
exported, so an input/Vault-provided token is actually honored on the
host instead of being regenerated. Empty stays empty so the no-arg
curl|bash install path still self-generates.
Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>