Fix release workflow: move secret check from job-level if to step script

secrets context is not available in job-level if conditions.
Guard the homebrew update step with a shell check instead.

Author: assimelha

.github/workflows/release.yml

@@ -127,14 +127,18 @@ jobs:
     needs: release
     runs-on: ubuntu-latest
     # Requires HOMEBREW_TAP_TOKEN secret: a PAT with push access to codingagentsystem/homebrew-cas
-    if: ${{ secrets.HOMEBREW_TAP_TOKEN != '' }}
     steps:
       - uses: actions/checkout@v4
 
       - name: Update Homebrew formula
         env:
           GH_TOKEN: ${{ secrets.HOMEBREW_TAP_TOKEN }}
         run: |
+          if [ -z "${GH_TOKEN}" ]; then
+            echo "HOMEBREW_TAP_TOKEN not set, skipping homebrew update"
+            exit 0
+          fi
+
           VERSION="${GITHUB_REF#refs/tags/v}"
 
           # Download and compute SHA256 for each platform