Limit cluster guessing to the interactive wizard

Revert the one-shot repo mirror create <url> to the fixed defaultClusterHost when [cluster-host] is omitted; catalog/jurisdiction-based cluster guessing is now confined to the no-args interactive wizard, so non-interactive invocations (and scripts) keep stable, predictable defaults. remove/collaborators were already on the fixed default and are unchanged.

Drops the one-shot-only resolveDefaultClusterHost/callerJurisdiction/ pickDefaultRegionHost helpers; the wizard keeps its jurisdiction-aware region pre-selection.