Permanently delete a user's account and all associated data.

Order matters:

1. Cancel the account's Paddle subscriptions. Nothing is deleted unless Paddle confirms: without a login the customer could not stop the charges themselves.
2. usage_logs → profiles has NO cascade, so wipe logs first or the auth.users delete fails with an FK violation.
3. auth.users delete cascades to profiles → connections (both have ON DELETE CASCADE).
4. Ask Paddle again. A checkout paid for during steps 1-3 was linked to the account after step 1 looked. Anything paid for after this is canceled by the webhook, which finds no account.

If step 3 fails after step 2 succeeded, the account is left with no usage history but otherwise intact. We log the partial state loudly so ops can reconcile, and return 500 so the client surfaces the error instead of signing the user out.