Migrate a React Native app from CometChat UI Kit v4 to v5 — the 16 removed components, what replaces each, the composite-to-modular rewrite, and the theming change from setter objects to a provider. Triggers: upgrade CometChat React Native v4 to v5, CometChatConversationsWithMessages removed, migrate RN chat uikit, CometChatDetails not found, v4 to v5 breaking changes.
