Regenerate TOTP Recovery Codes

Regenerate 10 new TOTP backup recovery codes. Primary body uses totp_code (6-digit). Fallback body for when the user burned their last backup code: { "password": "...", "recovery_code": "XXXXX-XXXXX" } — this fallback path CONSUMES the provided recovery code. Returns 10 plaintext codes once — they cannot be retrieved again.