Expo native modules

Description

Build and review custom native code for Expo apps with the Expo Modules API — deciding whether native code is needed, scaffolding local vs standalone modules with create-expo-module, the Swift/Kotlin module DSL (Name, Function, AsyncFunction, Property, Constant, Events, Records, enums, SharedObject), native views (View, Prop, EventDispatcher, requireNativeView), TypeScript bindings and types, threading and main-queue UI work, errors surfaced to JS, events with useEvent, lifecycle hooks (AppDelegate subscribers, Android activity/application listeners), config plugins that modify Info.plist/AndroidManifest/Gradle, expo-module.config.json and autolinking, dev builds, and testing. Use whenever the user needs functionality no Expo/RN package provides, wraps a platform SDK, writes Swift/Kotlin for an Expo app, edits a config plugin, or reviews native module code.