Use git short hash for image tag; remove confusing release name from CI: (tinkerbell#23)

## Description


The OCI image tag doesn't need the whole git hash, short hash is better.
Removing the release name from the CI artifacts job as it is confusing as it's not a GitHub release nor related to git tagging.

Fixes: #

## How Has This Been Tested?





## How are existing users impacted? What migration steps/scripts do we need?





## Checklist:

I have:

- [ ] updated the documentation and/or roadmap (if required)
- [ ] added unit or e2e tests
- [ ] provided instructions on how to upgrade

Author: mergify[bot]

.github/workflows/ci.yml

@@ -302,9 +302,9 @@ jobs:
           retention-days: 1
 
   # -------------------------------------------------------------------
-  # Collect release artifacts and compute checksums
+  # Publish artifacts and compute checksums
   # -------------------------------------------------------------------
-  release-artifacts:
+  publish-artifacts:
     runs-on: ${{ matrix.arch == 'arm64' && 'ubuntu-24.04-arm' || 'ubuntu-latest' }}
     needs: [build-iso]
     strategy:
@@ -354,13 +354,6 @@ jobs:
             out/initramfs-${{ matrix.arch }}.cpio.zst \
             out/captainos-${{ matrix.arch }}.iso
 
-      - name: Upload release artifacts
-        uses: actions/upload-artifact@v4
-        with:
-          name: release-${{ matrix.arch }}
-          path: out/
-          retention-days: 1
-
       - name: Log in to GHCR
         if: github.ref == 'refs/heads/main'
         uses: docker/login-action@v3
@@ -373,11 +366,15 @@ jobs:
         if: github.ref == 'refs/heads/main'
         uses: oras-project/setup-oras@v1
 
-      - name: Push release artifacts to GHCR
+      - name: Compute short SHA
+        id: short-sha
+        run: echo "sha=${GITHUB_SHA::7}" >> "$GITHUB_OUTPUT"
+
+      - name: Push artifacts to GHCR
         if: github.ref == 'refs/heads/main'
         run: |
           oras push \
-            ghcr.io/${{ github.repository }}/${{ env.OCI_ARTIFACT_NAME }}:${{ github.sha }}-${{ matrix.arch }} \
+            ghcr.io/${{ github.repository }}/${{ env.OCI_ARTIFACT_NAME }}:${{ steps.short-sha.outputs.sha }}-${{ matrix.arch }} \
             --annotation org.opencontainers.image.source=https://github.com/${{ github.repository }} \
             --annotation org.opencontainers.image.revision=${{ github.sha }} \
             out/vmlinuz-${{ matrix.arch }} \

.github/workflows/release.yml

@@ -28,11 +28,15 @@ jobs:
       - name: Load shared config
         run: cat .github/config.env >> "$GITHUB_ENV"
 
+      - name: Compute short SHA
+        id: short-sha
+        run: echo "sha=${GITHUB_SHA::7}" >> "$GITHUB_OUTPUT"
+
       - name: Pull release artifacts (amd64)
-        run: oras pull ghcr.io/${{ github.repository }}/${{ env.OCI_ARTIFACT_NAME }}:${{ github.sha }}-amd64 -o artifacts/amd64/
+        run: oras pull ghcr.io/${{ github.repository }}/${{ env.OCI_ARTIFACT_NAME }}:${{ steps.short-sha.outputs.sha }}-amd64 -o artifacts/amd64/
 
       - name: Pull release artifacts (arm64)
-        run: oras pull ghcr.io/${{ github.repository }}/${{ env.OCI_ARTIFACT_NAME }}:${{ github.sha }}-arm64 -o artifacts/arm64/
+        run: oras pull ghcr.io/${{ github.repository }}/${{ env.OCI_ARTIFACT_NAME }}:${{ steps.short-sha.outputs.sha }}-arm64 -o artifacts/arm64/
 
       - name: Create GitHub Release
         env:
@@ -47,8 +51,8 @@ jobs:
       - name: Tag OCI artifacts with version
         run: |
           oras tag \
-            ghcr.io/${{ github.repository }}/${{ env.OCI_ARTIFACT_NAME }}:${{ github.sha }}-amd64 \
+            ghcr.io/${{ github.repository }}/${{ env.OCI_ARTIFACT_NAME }}:${{ steps.short-sha.outputs.sha }}-amd64 \
             ${{ github.ref_name }}-amd64
           oras tag \
-            ghcr.io/${{ github.repository }}/${{ env.OCI_ARTIFACT_NAME }}:${{ github.sha }}-arm64 \
+            ghcr.io/${{ github.repository }}/${{ env.OCI_ARTIFACT_NAME }}:${{ steps.short-sha.outputs.sha }}-arm64 \
             ${{ github.ref_name }}-arm64