pip install does not work as documented

```
ubuntu@ip:~/briefer$ pip install briefer --break-system-packages --user
Requirement already satisfied: briefer in /home/ubuntu/.local/lib/python3.12/site-packages (0.0.14)
Requirement already satisfied: docker in /home/ubuntu/.local/lib/python3.12/site-packages (from briefer) (7.1.0)
Requirement already satisfied: requests in /usr/lib/python3/dist-packages (from briefer) (2.31.0)
Requirement already satisfied: urllib3>=1.26.0 in /usr/lib/python3/dist-packages (from docker->briefer) (2.0.7)
ubuntu@ip:~/briefer$ python3 -m briefer
/usr/bin/python3: No module named briefer.__main__; 'briefer' is a package and cannot be directly executed
ubuntu@ip:~/briefer$ briefer
briefer: command not found
ubuntu@ip:~/briefer$
```

Reproduce the documented pip command and the subsequent `python3 -m briefer` and `briefer` attempts; no source file or test is named in the issue. Inspect the Python package entry point and installation documentation, then verify that the documented install command exposes a working `briefer` command or clearly documents the supported invocation.

Written by the indexing model from the issue text.