Create stub files required by devcontainer bind mounts

Author: kiuma

.github/workflows/ci.yml

@@ -24,10 +24,13 @@ jobs:
           username: ${{ github.actor }}
           password: ${{ secrets.GITHUB_TOKEN }}
 
-      - name: Create dummy SSH auth socket for devcontainer
+      - name: Create stub files required by devcontainer bind mounts
         run: |
+          # SSH auth socket — no agent on CI runners
           touch /tmp/ssh-agent.sock
           echo "SSH_AUTH_SOCK=/tmp/ssh-agent.sock" >> $GITHUB_ENV
+          # git config — may not exist on a fresh runner
+          touch "${HOME}/.gitconfig"
 
       - name: Compute lowercase image name
         id: image_name