Implement customer and profile management views

[juliuskrah]

Parent initiative: #287

Summary

Implement customer and profile management views for commerce admin support workflows.

Acceptance criteria

• Customer and profile lists load from live GraphQL data with search, filters, empty states, and error states.
• Detail views show identity, profile, session, order, checkout, and basket relationships where the API exposes them.
• Permission-sensitive fields and actions render according to authorization responses from the API.
• Forms and read-only states handle validation, unavailable data, not found, and unauthorized outcomes.
• Unit/component tests cover list/detail rendering, relationship loading, permission states, form validation, and GraphQL error mapping.

Architecture note

gitstore-admin remains an optional add-on and consumes gitstore-api; it must not talk directly to gitstore-git-service.