Experiment with running amd64 builds on self-hosted and arm64 builds …

…on public runners

.github/workflows/workflow.yml

@@ -1,7 +1,7 @@
 name: CI (main and tags)
 on:
   push:
-    branches: [ "main" ]
+    branches: [ "ci" ]
     tags: [ "v*" ]
 permissions:
   checks: write
@@ -35,7 +35,7 @@ jobs:
           images: |
             ghcr.io/${{ github.repository }}
           tags: |
-            type=raw,value=latest,enable=${{ github.ref_name == 'main' }}
+            type=raw,value=latest,enable=${{ github.ref_name == 'ci' }}
             type=semver,pattern={{raw}}
 
   docker-build:
@@ -47,7 +47,7 @@ jobs:
     strategy:
       matrix:
         include:
-          - os: ubuntu-latest
+          - os: self-hosted
             arch: amd64
           - os: ubuntu-24.04-arm
             arch: arm64
@@ -68,7 +68,7 @@ jobs:
         uses: docker/metadata-action@v5
         with:
           tags: |
-            type=raw,value=latest,enable=${{ github.ref_name == 'main' }}
+            type=raw,value=latest,enable=${{ github.ref_name == 'ci' }}
             type=semver,pattern={{raw}}
           flavor: |
             latest=auto