Migrate Project scope ownership data to the Virtual Scope model

Migrate existing Project scope ownership rows in association_scopes_entities into the Virtual Scope chain: backfill virtual_scopes rows for existing Project owners, a self scope_binding per owner VS, scope_bindings for existing scope->Project links, and entity_memberships for existing Project->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-6663

Start by tracing the backend models and migration entry points for association_scopes_entities, virtual_scopes, scope_bindings, and entity_memberships, then read the alignment in BEP-1062 (#12842). Done means existing Project ownership, scope-to-Project links, and Project-to-child memberships are represented in the Virtual Scope chain, with ownership and permission regressions checked.

Written by the indexing model from the issue text.