Migrate Container Registry scope ownership data to the Virtual Scope model

Migrate existing Container Registry scope ownership rows in association_scopes_entities into the Virtual Scope chain: backfill virtual_scopes rows for existing Container Registry owners, a self scope_binding per owner VS, scope_bindings for existing scope->Container Registry links, and entity_memberships for existing Container Registry->child ownership. Verify no ownership/permission regressions after migration.

[Aligned to BEP-1062 (#12842): correct table names are virtual_scopes / scope_bindings / entity_memberships (previously scope_virtual / virtual_entity, which do not exist in code). Resolution is non-recursive; ownership resolves via the self scope_binding.]

JIRA Issue: BA-6664

Start by tracing the existing association_scopes_entities rows and the virtual_scopes, scope_bindings, and entity_memberships models. Use BEP-1062 (#12842) to confirm the table names and non-recursive ownership resolution. Done means existing Container Registry owners and links are backfilled correctly, with no ownership or permission regressions.

Written by the indexing model from the issue text.