Add bundled binary for CLI using PyInstaller

It would be nice to have a binary file for the CLI tool available for download (in Releases section, next to the archive of the source code) for systems without python installed. I've used pyinstaller in my local fork, and it seems to work just fine for my use case, but 2 things arise:

1. I think this would require another test harness; and
2. I think this breaks runtime plugin support.

This might be a dealbreaker, so an alternative to bundling might be to just add instructions to the installation section of the docs. Here's what I've used:

% uv venv
% source .venv/bin/activate.fish
% uv pip install -e . pyinstaller

This creates the environment and installs dependencies. Then create cli.py with the following content:

from sqlite_utils.cli import cli

if __name__ == "__main__":
	cli()

And then bundle and do a quick sanity check:

% pyinstaller --onefile --name sqlite-utils --copy-metadata sqlite-utils cli.py
% cd dist/
% ./sqlite-utils --version
% ./sqlite-utils create-table my.db people id integer name text height float --pk id --strict

Thanks for sqlite-utils :)

First clarify whether the goal is a PyInstaller binary in Releases or installation instructions, since the issue leaves both options open and flags plugin and test-harness concerns. Start from the proposed cli.py entry point importing sqlite_utils.cli.cli, then run the listed PyInstaller commands and sanity checks for --version and create-table. Done means the chosen approach is documented and verified, including its plugin and testing implications.