Machine identity v1 stable errors

Code	Meaning	Retry
`machine_token_missing`	Authorization bearer token is absent or malformed	No, fix request
`machine_token_invalid`	Header, claims, signature, request binding or key is invalid	No
`machine_token_expired`	Token is outside its accepted time window	Mint a new token
`machine_audience_denied`	Exact audience does not match	No
`machine_scope_denied`	Required scope is absent or not granted to the key	No
`machine_identity_revoked`	Principal or key is disabled/revoked	No; operator action
`machine_token_replayed`	The same principal/jti was already accepted	Retry with a new token and the same business idempotency key
`machine_transport_required`	HTTPS policy is not satisfied	No; fix deployment

Responses and audit facts never include the token, signature, key material or Authorization header.