Publish `@finos/git-proxy-cli` to npm, check quickstart guide accuracy

`@finos/git-proxy-cli` has [never been published to NPM](`https://registry.npmjs.org/@finos%2fgit-proxy-cli`). Meanwhile, both the installation docs and the quickstart approval walkthrough tell users to install and run it, so those commands fail with a 404.

Prior to `2.0.0` (last verified version is `2.0.0-rc.5`), `@finos/git-proxy` [shipped on NPM with the package/git-proxy-cli included](https://www.npmjs.com/package/@finos/git-proxy/v/2.0.0-rc.5?activeTab=code). We started shipping just the `dist` folder instead of the whole source, however CLI publishing wasn't set up to allow users to access CLI directly.

### Broken commands in the docs

- `docs/installation`: `npm install -g @finos/git-proxy-cli`
- `docs/installation`: `npm install -g @finos/git-proxy-cli@1.0.0` (version never existed)
- `docs/quickstart/approve`: `npx -- @finos/git-proxy-cli login --username admin --password admin`

**Describe the solution you'd like**

`packages/git-proxy-cli/package.json` on `main` is already good to publish, only the release workflow is missing.

**Additional context**
Discussion in #1652 where we realized something was wrong

### Blocked by
#1520 and #1627, both touching our release process.

Start with packages/git-proxy-cli/package.json and the release process, then review the installation and quickstart/approve documentation commands. Check the release workflow changes needed after blockers #1520 and #1627. Done means the CLI is published to NPM and the documented install and npx commands work, including checking the version-specific command.

Written by the indexing model from the issue text.