fix(ci): address PR review feedback on staging-ci [skip-regression-check]

- Remove broken skip-claude-gate label check (label always exists after
  bootstrap); keep only workflow_dispatch input override
- Require claude-review.result == 'success' in gate condition so a
  crashed review blocks promotion instead of silently passing
- Load review prompt into GITHUB_ENV instead of $(cat) in YAML with:
  block (YAML doesn't do shell substitution)
- version-check roll-up: check != 'success' instead of == 'failure'
  to catch cancelled/skipped states
- Force run: set diff_range to valid empty range when no new commits
- Align low-confidence label spacing in create-labels.sh

Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>

.github/workflows/code_style.yml

@@ -69,7 +69,7 @@ jobs:
             echo "One or more jobs failed"
             exit 1
           fi
-          if [[ "${{ needs.version-check.result }}" == "failure" ]]; then
-            echo "Version bump check failed"
+          if [[ "${{ needs.version-check.result }}" != "success" ]]; then
+            echo "Version bump check did not succeed (status: ${{ needs.version-check.result }})"
             exit 1
           fi