[Tommy Nguyen (tido64)]

Description

Scheduled nightly builds fail because metro-config@0.87.2 (and ob1) are quarantined by npmMinimalAgeGate.

Pre-approval is only needed when testing react-native@nightly or templates on CI, so this moves the list from .yarnrc.yml to a workflow-level YARN_NPM_PREAPPROVED_PACKAGES env var in build.yml. Yarn splits array settings from env vars on commas. It also adds metro, metro-*, and ob1.

Platforms affected

• Android
• iOS
• macOS
• visionOS
• Windows

Test plan

export YARN_NPM_PREAPPROVED_PACKAGES="@react-native-community/*,@react-native/*,flow-estree,flow-parser,hermes-compiler,metro,metro-*,ob1,react-native,react-native-macos,react-native-windows"
cd packages/app
node --run set-react-version -- nightly
yarn install --mode=update-lockfile  # resolves without YN0016

Without the env var, yarn config get npmPreapprovedPackages returns [] locally.