feat: add Artifact Hub metadata and GitHub Actions release workflow

Artifact Hub requires a GitHub-hosted repo for Headlamp plugins.
Since Gitea push-mirrors git objects but not releases, a GitHub
Actions workflow builds and publishes GitHub Releases with the
tarball that Artifact Hub needs.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

artifacthub-pkg.yml

@@ -0,0 +1,28 @@
+version: 0.0.1
+name: polaris-headlamp-plugin
+displayName: Polaris
+createdAt: "2026-02-05T19:00:00Z"
+description: Surfaces Fairwinds Polaris audit results inside the Headlamp UI.
+license: MIT
+homeURL: "https://github.com/cpfarhood/polaris-headlamp-plugin"
+category: security
+keywords:
+  - polaris
+  - fairwinds
+  - security
+  - audit
+  - headlamp
+  - kubernetes
+links:
+  - name: Source
+    url: "https://github.com/cpfarhood/polaris-headlamp-plugin"
+  - name: Polaris
+    url: "https://polaris.docs.fairwinds.com/"
+maintainers:
+  - name: cpfarhood
+    email: ""
+annotations:
+  headlamp/plugin/archive-url: "https://github.com/cpfarhood/polaris-headlamp-plugin/releases/download/v0.0.1/polaris-headlamp-plugin-0.0.1.tar.gz"
+  headlamp/plugin/version-compat: ">=0.26"
+  headlamp/plugin/archive-checksum: sha256:456f09cf8b126816b80c723b6c6f300b2af0c2e1288ee67da13f435b0e35c04d
+  headlamp/plugin/distro-compat: in-cluster