Bulk Invite Personnel

Invite many employees at once, each as a full personnel + WorkOS user record, each on the row's shop_role_id (owner-only) or the global floor role. The shop's own owner reassigns roles afterward via the existing Personnel UI — this endpoint exists to get a roster onto the platform on day one without deciding everyone's role up front.

Per-invite failures don't abort the batch — each entry reports its own outcome.