Email a code to confirm deleting your account

Dashboard session only, with the account's email typed to confirm and the code from `POST /account/deletion/code` (`400 email_mismatch`, `400 invalid_code`). Fails with `409 account_deletion_blocked`, listing the blocking organizations, while any blocker from `GET /account/deletion` remains; nothing changes then. Otherwise every organization you are the last owner of is deleted like `DELETE /organizations/:organizationId` and its contacts, signup confirmations, recipient addresses and raw webhook payloads are erased (suppression hashes stay); you leave every other organization and team; your sessions, sign-in methods, OAuth tokens and consents end; and your name and email are erased. Billing records and audit events keep an anonymous id. Signing in again with the same email creates a new, empty account. **Authentication:** Requires a dashboard session cookie; OAuth access tokens and API keys are not accepted. Requests must pass the dashboard's same-origin and CSRF checks. Sensitive billing actions require recent authentication and a single-use billing action token; POST /billing/action-token issues that token.