fix(ci): add missing branch output to auto-release version step

Step 2 (Version archive branch) failed because steps.version.outputs.branch
was empty. Added branch=version/MAJOR to Step 1 outputs.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.mokogitea/workflows/auto-release.yml

@@ -98,6 +98,7 @@ jobs:
           echo "version=${VERSION}" >> "$GITHUB_OUTPUT"
           echo "release_tag=v${MAJOR}" >> "$GITHUB_OUTPUT"
           echo "skip=false" >> "$GITHUB_OUTPUT"
+          echo "branch=version/${MAJOR}" >> "$GITHUB_OUTPUT"
 
       - name: "Step 1b: Bump version"
         id: bump