Resend Invite

Re-send the candidate invitation email for an existing interview.

Replaces the old FE-direct POST to /api/interviews/send-invitation, which sent neither company_name nor job_title — the email route's trust guard 400s when both are blank, so the resend button silently failed. Identity MUST resolve server-side (resolve_for_read applies the role's CURRENT visibility — a role flipped to Confidential after dispatch must hide the name on resends too), and resolving here also restores the brain framing, coding heads-up, and plan-round callout the FE path couldn't compute.