fix: handle detached HEAD in release workflow

The release workflow was in detached HEAD state when checking out
tags, causing push failures. Now explicitly checks out main branch
and pulls before committing submodule updates.

This fixes the "non-fast-forward" error in the release automation.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: github-actions[bot]

.github/workflows/release.yml

@@ -117,6 +117,9 @@ jobs:
           if git diff --quiet Formula/axon.rb; then
             echo "No changes to formula"
           else
+            # Ensure we're on main branch in submodule
+            git checkout main
+            git pull origin main
             git add Formula/axon.rb
             git commit -m "Update AXON formula for ${TAG_NAME}"
             git push origin main
@@ -125,13 +128,17 @@ jobs:
 
           # Update submodule reference in main repo
           cd ..
+
+          # Ensure we're on main branch
+          git checkout main
+          git pull origin main
           git add homebrew-tap
 
           if git diff --staged --quiet; then
             echo "No submodule changes to commit"
           else
             git commit -m "Update homebrew-tap submodule for ${TAG_NAME}"
-            git push origin HEAD:main
+            git push origin main
             echo "✓ Updated submodule reference in main repo"
           fi