feat(registry): preserve release manifest

[MarcStdt]

Summary

• add a shared --preserve-release-manifest option to druid push and druid pull
• include the installed release descriptor only for snapshot transfers
• restore the descriptor carried by a backup instead of replacing it with the backup descriptor
• reject preservation-mode backups that lack a valid descriptor

Verification

• go test ./internal/core/services/registry ./apps/druid/adapters/cli

Stack

Foundational druid-cli runtime contract for the Unified Scroll Lifecycle. Backup/restore orchestration and explicit deployment update controls depend on this behavior and will follow in later PRs.

[druid-infra]

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