Professional guide to Ably Realtime for building real-time React/TypeScript applications with pub-sub messaging, channels, presence tracking, Spaces (collaborative UI), LiveObjects (shared state), Chat SDK (complete messaging), and LiveSync (database synchronization). Use when working with Ably, real-time messaging, WebSockets, pub-sub, channels, presence, collaborative features, live cursors, avatar stacks, component locking, shared state, conflict-free updates, chat rooms, typing indicators, message reactions, database sync, outbox pattern, useChannel, usePresence, useSpace, useMembers, useCursors, useMessages, useTyping, LiveCounter, LiveMap, or integrating Ably with Neon/PostgreSQL for persistent real-time data.