Terminal success/failure closes kept the acceptance-phase operation state,
emitting self-contradicting envelopes (outcome=success with state=processing).
WithOperationTerminalState now closes the envelope at the observed terminal
status and clears timed_out.
WaitSpec.Validate trimmed status values only for checking and never wrote them
back, so padded declarations passed validation, published a padded Schema, and
then fail-closed at runtime as unknown statuses. NormalizeWaitSpec is now the
single canonical form shared by declaration (corecmd.New / AttachContract),
ToolSpec, and validation: trimmed values, duplicate/conflict rejection,
defensive copy.
Also covers the waitTimeoutDuration secs<=0 branch flagged by the coverage
gate.