chore(e2e): enable RN 0.81+ iOS prebuilt pods in example setup

[floydkim]

Summary

Updated the example app setup flow so React Native 0.81.x to 0.83.x examples use React Native iOS prebuilt artifacts during pod install.

With this change:

• The existing setup:pods npm script now runs different iOS pod install commands depending on the React Native version.
• The checked-in RN 0.81.6, 0.82.1, and 0.83.2 example apps were refreshed to match the same rule.

Changes

• Updated setup-example-app so the generated setup:pods script is version-aware
• RN 0.81.x to 0.83.x
  • RCT_USE_RN_DEP=1 RCT_USE_PREBUILT_RNCORE=1 bundle exec pod install
• RN < 0.81.0
  • keeps the existing bundle exec pod install
• RN >= 0.84.0
  • keeps the default React Native behavior

Expected Impact

• Reduces iOS dependency installation time for RN 0.81+ example apps