Add deployment registry selection to cre init

[ejacquier]

Add deployment registry selection to cre init

When initializing a new project, users are now prompted to choose which registry their workflows will deploy to. This makes the registry choice
explicit at project creation time rather than leaving it as an implicit default.

What changed:

• cre init wizard — new registry selection step after workflow name. Private (off-chain) registries appear first with the cursor defaulted to them.
  Includes a two-line description explaining the trade-off (private = no gas, quick testing; on-chain = production/multisig).
• --deployment-registry flag — new flag on cre init. Required in --non-interactive mode. Skips the wizard step when provided.
• workflow.yaml output — the selected registry ID is written as deployment-registry in both staging-settings and production-settings targets. Omitted
  when empty (backward compatible — existing files without the field continue to default to on-chain).
• Fallback handling — if the org has no registries configured, a warning is printed and the step is skipped silently.

Backward compatibility: existing workflow.yaml files without deployment-registry are unaffected — ResolveRegistry already defaults to the on-chain
registry from EnvironmentSet when the field is absent.

[github-actions]

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