[codex] publish npm packages concurrently (#27527)

In https://github.com/openai/codex/actions/runs/27308011621,
publishing the npm tarballs serially took 147 seconds. Six platform
packages and the responses API proxy are independent.

Publish those packages concurrently, then publish the root CLI wrapper
and SDK in dependency order. Individual platform publishes took 19 to
23 seconds, so this should reduce total release time by nearly two
minutes.

.github/workflows/rust-release.yml

@@ -1355,19 +1355,15 @@ jobs:
             other_tarballs+=("${tarball}")
           done
 
-          # Publish the platform packages before the root CLI wrapper. The root
-          # wrapper advances @openai/codex@latest, so it should only publish
-          # after the optional dependency versions it references exist.
-          tarballs=(
-            "${platform_tarballs[@]}"
-            "${other_tarballs[@]}"
-            "${root_tarball}"
-          )
-          if [[ -f "${sdk_tarball}" ]]; then
-            tarballs+=("${sdk_tarball}")
-          fi
+          publish_tarball() {
+            local tarball="$1"
+            local filename
+            local tag
+            local platform
+            local publish_output
+            local publish_status
+            local -a publish_cmd
 
-          for tarball in "${tarballs[@]}"; do
             filename="$(basename "${tarball}")"
             tag=""
 
@@ -1382,7 +1378,7 @@ jobs:
                 ;;
               *)
                 echo "Unexpected npm tarball: ${filename}"
-                exit 1
+                return 1
                 ;;
             esac
 
@@ -1399,16 +1395,34 @@ jobs:
 
             echo "${publish_output}"
             if [[ ${publish_status} -eq 0 ]]; then
-              continue
+              return 0
             fi
 
             if grep -qiE "previously published|cannot publish over|version already exists" <<< "${publish_output}"; then
               echo "Skipping already-published package version for ${filename}"
-              continue
+              return 0
             fi
 
-            exit "${publish_status}"
-          done
+            return "${publish_status}"
+          }
+
+          # Publish independent packages concurrently, but wait for all of
+          # them before publishing the root CLI wrapper.
+          independent_tarballs=(
+            "${platform_tarballs[@]}"
+            "${other_tarballs[@]}"
+          )
+
+          export prefix
+          export -f publish_tarball
+          printf '%s\0' "${independent_tarballs[@]}" |
+            xargs -0 -n1 -P0 bash -c "publish_tarball \"\$1\"" _
+
+          publish_tarball "${root_tarball}"
+          # The SDK depends on this exact root package version.
+          if [[ -f "${sdk_tarball}" ]]; then
+            publish_tarball "${sdk_tarball}"
+          fi
 
   deploy-dev-website:
     name: Trigger developers.openai.com deploy