logs.clear removes prompt

[schneems]

This

  ```term
  :::>> print.erb
  $ heroku run:inside <%= `heroku ps --json | jq -r ".[0].name"`.strip %> "launcher bash"
  :::-- background.start('heroku run:inside $(heroku ps --json | jq -r ".[0].name") "launcher bash"', wait: "$", timeout: 120, name: "heroku_run")
  :::-- background.stdin_write("ruby -v", name: "heroku_run", wait: "$", timeout: 30)
  :::-- background.stdin_write("rails -v", name: "heroku_run", wait: "$", timeout: 30)
  :::-- background.stdin_write("ls -lah", name: "heroku_run", wait: "$", timeout: 30)
  :::-> background.log.read(name: "heroku_run")
  :::-- background.log.clear(name: "heroku_run")
  ```
  
  If you receive an error, `Error connecting to process`, [configure your firewall](https://devcenter.heroku.com/articles/troubleshooting-one-off-dynos-awaiting-process-timeout-issues).
  
  You can run any command this way such as `launcher rails console` or `launcher rake db:migrate`. Type `exit` to exit the shell and terminate the dyno:
  
  ```term
  :::-- background.stdin_write("exit", name: "heroku_run", wait: "exit")
  :::-> background.stop(name: "heroku_run")
  ```

Produces this output:

  drwxr-xr-x. 3 heroku heroku   20 Jan  1  1980 vendor
  heroku@web-549d786c64-c65nv:/workspace$ ruby -v
  ruby 3.2.4 (2024-04-23 revision af471c0e01) [aarch64-linux]
  heroku@web-549d786c64-c65nv:/workspace$ rails -v
  Rails 7.1.3.2
  heroku@web-549d786c64-c65nv:/workspace$
  ```
  <!-- STOP. This document is autogenerated. Do not manually modify. See the top of the doc for more details. -->
  
  If you receive an error, `Error connecting to process`, [configure your firewall](https://devcenter.heroku.com/articles/troubleshooting-one-off-dynos-awaiting-process-timeout-issues).
  
  You can run any command this way such as `launcher rails console` or `launcher rake db:migrate`. Type `exit` to exit the shell and terminate the dyno:
  
  ```term
  exit
  exit
  ```

Because of the way I'm clearing the logs between the invocations it gets rid of the prompt. Maybe an argument that preserves the last N lines? I'm not sure what to call it though.