fix(ci): block release on failed validator chain

.gitea/workflows/prepare-release.yml

@@ -19,11 +19,23 @@ concurrency:
   cancel-in-progress: false
 
 jobs:
+  upstream-gate:
+    name: Upstream Success Gate
+    runs-on: ubuntu-latest
+    steps:
+      - name: Fail Fast on Failed Validator Chain
+        run: |
+          if [ "${{ github.event_name }}" = "workflow_run" ] && [ "${{ github.event.workflow_run.conclusion }}" != "success" ]; then
+            echo "ERROR: Validators workflow did not succeed; release preparation is blocked."
+            exit 1
+          fi
+
   build-and-release:
     name: Build & Create Release
     if: ${{ github.event_name == 'workflow_dispatch' || github.event.workflow_run.conclusion == 'success' }}
     runs-on: ubuntu-latest
     timeout-minutes: 30
+    needs: upstream-gate
     outputs:
       version: ${{ steps.metadata.outputs.version }}
       commit: ${{ steps.metadata.outputs.commit }}
@@ -199,7 +211,7 @@ jobs:
     name: Release Notification
     runs-on: ubuntu-latest
     if: always()
-    needs: build-and-release
+    needs: [upstream-gate, build-and-release]
 
     steps:
       - name: Notify Release Ready