refactor: standardize variable bracing syntax in release workflows

Improve code consistency by using ${VAR} syntax instead of $VAR
for all variable references in release workflows.

Changes:
- Use ${TAG_NAME} for git tag and push commands in both ATS and MP workflows
- Use ${MP_PACKAGES_TO_BUMP} in Mass Payout validation message

This addresses PR feedback for improved consistency and follows bash
best practices for variable expansion.

Addresses: PR #645 comments #3 and #5 from andrewb1269hg

Signed-off-by: Miguel_LZPF <[email protected]>

Author: MiguelLZPF

.github/workflows/ats.release.yml

@@ -134,8 +134,8 @@ jobs:
           echo "📦 Creating ATS release: $TAG_NAME"
 
           # Create and push tag
-          git tag "$TAG_NAME"
-          git push origin "$TAG_NAME"
+          git tag "${TAG_NAME}"
+          git push origin "${TAG_NAME}"
 
           # Generate release notes from ATS package changelogs
           RELEASE_NOTES=""

.github/workflows/mp.release.yml

@@ -73,7 +73,7 @@ jobs:
             exit 1
           fi
 
-          echo "✅ Found $MP_PACKAGES_TO_BUMP Mass Payout package(s) ready for release"
+          echo "✅ Found ${MP_PACKAGES_TO_BUMP} Mass Payout package(s) ready for release"
 
           # Show which packages will be bumped
           echo "📦 Mass Payout packages to be released:"
@@ -134,8 +134,8 @@ jobs:
           echo "📦 Creating Mass Payout release: $TAG_NAME"
 
           # Create and push tag
-          git tag "$TAG_NAME"
-          git push origin "$TAG_NAME"
+          git tag "${TAG_NAME}"
+          git push origin "${TAG_NAME}"
 
           # Generate release notes from Mass Payout package changelogs
           RELEASE_NOTES=""