Merge pull request #89 from SprocketBot/codex/sanitize-ghcr-branch-tags

[codex] Sanitize GHCR image tags for branch names

Author: gankoji

.github/workflows/docker-image.yml

@@ -35,9 +35,12 @@ jobs:
         username: ${{ github.actor }}
         password: ${{ secrets.GITHUB_TOKEN }}
 
-    - name: Extract branch name
+    - name: Extract image tag
       shell: bash
-      run: echo "branch=${GITHUB_HEAD_REF:-${GITHUB_REF#refs/heads/}}" >> "$GITHUB_OUTPUT"
+      run: |
+        raw_ref="${GITHUB_HEAD_REF:-${GITHUB_REF#refs/heads/}}"
+        safe_tag="$(echo "$raw_ref" | tr '[:upper:]' '[:lower:]' | sed 's|[^a-z0-9._-]|-|g')"
+        echo "branch=$safe_tag" >> "$GITHUB_OUTPUT"
       id: extract_branch
 
     - name: Build And Push Image