refactor: store Zalo hosted media in plugin state

Move Zalo hosted outbound media metadata and expiry into plugin state, add SDK chunked hosted media storage, and keep CI/type/lint gates green after rebase.

.github/workflows/ci.yml

@@ -722,7 +722,7 @@ jobs:
 
           if [ "$RUN_GATEWAY_WATCH" = "true" ]; then
             start_check "gateway-watch" \
-              node scripts/check-gateway-watch-regression.mjs --skip-build --ready-timeout-ms 5000
+              node scripts/check-gateway-watch-regression.mjs --skip-build
           fi
 
           for index in "${!pids[@]}"; do