Replace deprecated `mc config host add` with `mc alias set`.
## Context
Running the current **createbuckets** service logs errors similar to:
```
mc: <ERROR> `config` is not a recognized command. Get help using `--help` flag.
mc: <ERROR> Unable to set anonymous `public` for `minio/typebot/public`. Requested path `/minio/typebot/public` not found.
```
These arise because the command `mc config host` add was removed in
recent releases in favor of `mc alias set`. Without a valid alias,
subsequent commands reference a non‑existent path and fail.
`--ignore-existing` – makes bucket creation idempotent so the service
can run multiple times without failing.
