ci: harden live release validation lane

.github/workflows/openclaw-live-and-e2e-checks-reusable.yml

@@ -1370,8 +1370,16 @@ jobs:
         run: |
           set -euo pipefail
           if ! command -v ffmpeg >/dev/null 2>&1; then
-            sudo apt-get update
-            sudo DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends ffmpeg
+            for attempt in 1 2 3; do
+              if sudo apt-get update -o Acquire::Retries=3; then
+                break
+              fi
+              if [[ "${attempt}" == "3" ]]; then
+                exit 1
+              fi
+              sleep $((attempt * 5))
+            done
+            sudo env DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends ffmpeg
           fi
           ffmpeg -version | head -1