Relocate artifact registry organization page to ee/

What does this MR do and why?

Relocates the Artifact Registry organization Activation page from FOSS into ee/, so the feature is EE-only. This is S01 Step 2 of the Artifact Registry Vue app shell (the Platform foundation the later AR slices build on); it makes no AR call and defines no AR GraphQL or client.

Changes:

• Move the AR organization controller (the slug-less #index), its placeholder view, and the slug-less index route from FOSS into ee/, and switch the controller to feature_category :artifact_registry (from :organization).
• Keep the read_artifact_registry grant for organization_user in the core organization policy (per review): admins already receive it in core via the admin role config, so keeping the organization-member grant in core too avoids a CE/EE split in authorization logic and eases the migration to the new auth stack. The controller still enforces read_artifact_registry, so the feature stays EE-only.
• Regenerate the js-routes path helpers: artifactRegistryOrganizationIndexPath is dropped from the FOSS bundle and added to the EE bundle.
• Repoint the EE organizations/show overview override to import artifactRegistryOrganizationIndexPath from ee/lib/utils/path_helpers/organizations (the FOSS bundle no longer exports it after the route move), fixing an organization-overview page crash.

EE behavior is preserved (the slug-less .../-/artifact_registry path still renders identically); on a FOSS build the route is absent (404). This slice ships dark behind the existing ui_for_organizations flag, so there is no changelog entry yet.

References

• Related to #604731 (closed).

Screenshots or screen recordings

No user-visible change on an EE build - this is a pure relocation. Verified live on GDK: the organization overview page renders the "Go to Artifact Registry" link (href .../-/artifact_registry) with a clean console, and the relocated Activation placeholder ("Artifact registry") renders for an organization member (404 for non-members).

Before	After
Org overview + AR Activation placeholder render on an EE build	Identical, with the controller, view, and route now under ee/

How to set up and validate locally

1. Enable the organization UI flag in the rails console:

   Feature.enable(:ui_for_organizations)

2. As an organization member, visit the org overview /-/organizations/<organization_path>/-/overview (or /o/<organization_path>/-/overview): the "Go to Artifact Registry" link renders and points to .../-/artifact_registry (regression guard for the js-routes import repoint).
3. Visit .../-/artifact_registry: the Activation placeholder renders on EE; a non-member gets a 404.
4. Run the specs:

   bundle exec rspec ee/spec/requests/organizations/artifact_registry_controller_spec.rb ee/spec/routing/organizations/artifact_registry_routing_spec.rb ee/spec/policies/organizations/organization_policy_spec.rb spec/policies/organizations/organization_policy_spec.rb
   yarn jest ee/spec/frontend/organizations/show spec/frontend/organizations/show

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