refactor: move to single-repo pattern for releases

Switch from dual-repo (stable + dev) to single-repo pattern where both
stable and dev releases are published to the same GitHub repository.

Changes:
- Remove GITHUB_REPO routing logic (was causing releases to wrong repo)
- Hardcode all GitHub URLs to cpfarhood/headlamp-polaris-plugin
- Update dev branch metadata to point to main repo
- Keep prerelease flag in metadata for ArtifactHub differentiation
- Workflow pushes both stable and dev releases to same repo
- ArtifactHub will show dev releases under "Include prereleases" toggle

This follows the standard mono-repo release pattern (like Node.js, K8s)
where users see one package with stable/prerelease versions.

artifacthub-pkg.yml

@@ -12,7 +12,7 @@ description: >-
   Requires a Role granting `get` on `services/proxy` for the
   `polaris-dashboard` service in the `polaris` namespace.
 license: MIT
-homeURL: "https://github.com/cpfarhood/headlamp-polaris-plugin-dev"
+homeURL: "https://github.com/cpfarhood/headlamp-polaris-plugin"
 category: security
 keywords:
   - polaris
@@ -23,8 +23,6 @@ keywords:
   - kubernetes
 links:
   - name: Source
-    url: "https://github.com/cpfarhood/headlamp-polaris-plugin-dev"
-  - name: Main Repository
     url: "https://github.com/cpfarhood/headlamp-polaris-plugin"
   - name: Polaris
     url: "https://polaris.docs.fairwinds.com/"
@@ -32,7 +30,7 @@ maintainers:
   - name: cpfarhood
     email: "chris@farhood.org"
 annotations:
-  headlamp/plugin/archive-url: "https://github.com/cpfarhood/headlamp-polaris-plugin-dev/releases/download/v0.2.0-dev.3/headlamp-polaris-plugin-0.2.0-dev.3.tar.gz"
+  headlamp/plugin/archive-url: "https://github.com/cpfarhood/headlamp-polaris-plugin/releases/download/v0.2.0-dev.3/headlamp-polaris-plugin-0.2.0-dev.3.tar.gz"
   headlamp/plugin/version-compat: ">=0.26"
   headlamp/plugin/archive-checksum: sha256:0000000000000000000000000000000000000000000000000000000000000000
   headlamp/plugin/distro-compat: in-cluster