Move release process to GitHub Action

Following a mistake during our execution of the deploy steps for v1.7.2, that version of this plugin went live without built assets. That caused errors in downstream projects which used `hm.controls.PostControl` as a dependency.

To avoid human error, we should update this project to use a GitHub Action-based release workflow that publishes the built tag and release in an automated fashion.

Start by locating the project’s current manual deploy and release steps, along with the process that builds its assets. Use those entry points to define a GitHub Actions release workflow for tagged versions. Done means a tag automatically builds the assets and publishes the corresponding release without manual deployment steps.

Written by the indexing model from the issue text.