feat: add Docker build and release call workflow Action

[rainest]

Description

Add a callable workflow that takes a Dockerfile, target, a registry, and desired platforms, builds images, and pushes them to the registry, and creates attestations.

Keeps some of the inputs from the Goreleaser workflow, but not all. I removed some stuff that looked unecessary (because it could be done in the Dockerfile instead) or where it looked like there were better options for reasonable defaults.

If the pushed ref is a tag, create a release for it, unless the release already exists.

Checklist

• My code follows the style guidelines of this project
• I have added/updated comments where needed
• I have added tests that prove my fix is effective or my feature works
• I have run make test (or equivalent) locally and all tests pass
• DCO Sign-off: All commits are signed off (git commit -s) with my real name and email
• REUSE Compliance:
  • Each new/modified source file has SPDX copyright and license headers
  • Any non-commentable files include a <filename>.license sidecar
  • All referenced licenses are present in the LICENSES/ directory

Not sure on the licensing stuff, there aren't many other examples in the other workflows.

Type of Change

• Bug fix
• New feature
• Breaking change
• Documentation update

[rainest]

See chat discsussion at (for now) https://openchami.slack.com/archives/C099YK6M3A8/p1759448033651679 and https://openchami.slack.com/archives/C099YK6M3A8/p1760730373971579

https://github.com/rainest/power-control/actions/runs/18701210581 is an example run called from the PR branch, which created release https://github.com/rainest/power-control/releases/tag/v2.9.10.

There's no slack announcement of this (shouldn't be, it's a fork), though I'm not entirely sure how the slack announcements are running currently.

[rainest]

Unsure how to make the linters happy. Some of that's complaints about existing code, some of it's complaints about the added stuff, but IDK how to fix it--shellcheck against embedded shell inside YAML is kinda confusing about the specifics of what it's complaining about, and it'll point to line number that don't make sense or that don't appear to have the problem it describes.

I want to add @taylorludwig as a reviewer but cannot for whatever reason.

[alexlovelltroy]

I think this looks good. If you can give me write access on your fork, I can fix the linter stuff.

[rainest]

I may be able to use not a fork in the future (I often use them when I need to test Actions stuff, but I think it's fine to just call a branch or hash version of an action. Given the existing open PR here though, I've just added @alexlovelltroy to my fork as a collaborator to take a stab at making the linter happier if we wanna bother (main's currently broken anyway, so maybe we don't really care).