Profile page: replace raw useState with reactive useUser() from tlv2-auth

[irees]

Summary

The profile page (app/pages/admin/profile.vue) bypasses useUser() and directly accesses useState('auth0_user') and useState('tlv2_user_roles') because useUser() is not reactive to session enrichment in @interline-io/tlv2-auth.

This couples the page to internal state key names that could change in tlv2-auth.

What needs to happen

1. Fix useUser() in @interline-io/tlv2-auth so it returns reactive state that updates after session enrichment (e.g., when roles are fetched)
2. Update app/pages/admin/profile.vue to use useUser() instead of raw useState calls
3. Remove the TODO comment

Context

Introduced in #324 (tlv2-ui → tlv2-auth migration). See app/pages/admin/profile.vue:31-39.