Add secret check step to deploy workflow for token length verification

.forgejo/workflows/deploy.yml

@@ -23,6 +23,14 @@ jobs:
             --exclude='node_modules/' \
             ./ "${DEPLOY_DIR}/"
 
+      - name: Secret check
+        env:
+          WEBMENTION_TOKEN: ${{ secrets.WEBMENTION_TOKEN }}
+          WEBMENTION_APP_TOKEN: ${{ secrets.WEBMENTION_APP_TOKEN }}
+        run: |
+          echo "WEBMENTION_TOKEN length: ${#WEBMENTION_TOKEN}"
+          echo "WEBMENTION_APP_TOKEN length: ${#WEBMENTION_APP_TOKEN}"
+
       - name: Build image
         run: |
           cd "${DEPLOY_DIR}"