fix(ci): use stream tag 'stable' instead of version tag 'vXX'

Release tags should use update stream names (stable, development,
release-candidate) not version-based tags (v02, v03). This aligns
with the pre-release workflow which already uses stream tags.

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

.mokogitea/workflows/auto-release.yml

@@ -96,9 +96,9 @@ jobs:
           fi
           MAJOR=$(echo "$VERSION" | cut -d. -f1)
           echo "version=${VERSION}" >> "$GITHUB_OUTPUT"
-          echo "release_tag=v${MAJOR}" >> "$GITHUB_OUTPUT"
+          echo "release_tag=stable" >> "$GITHUB_OUTPUT"
           echo "skip=false" >> "$GITHUB_OUTPUT"
-          echo "branch=version/${MAJOR}" >> "$GITHUB_OUTPUT"
+          echo "branch=main" >> "$GITHUB_OUTPUT"
 
       - name: "Step 1b: Bump version"
         id: bump