feat: expose internal contexts and composer components in the public API

These components/hooks/contexts were used internally and referenced by the
docs but were never re-exported from the package barrels, so consumers could
not import them. Wire them into the public API:

- context: VirtualizedMessageListContext, VirtualizedMessageListContextProvider,
  useVirtualizedMessageListContext, VirtualizedMessageListContextValue
- components: SummarizedMessagePreview + useLatestMessagePreview (and its
  ChannelPreviewMessageType / ChannelPreviewDeliveryStatus /
  LatestMessagePreviewData / UseLatestMessagePreviewParams types)
- message composer: VoiceRecordingPreviewSlot component; MessageComposerActions
  and AdditionalMessageComposerActions

Purely additive barrel re-exports; no behavior change. yarn types and eslint pass.

Author: oliverlaz

src/components/MessageComposer/index.ts

@@ -1,5 +1,8 @@
 export * from './AttachmentSelector';
-export { AttachmentPreviewList } from './AttachmentPreviewList';
+export {
+  AttachmentPreviewList,
+  VoiceRecordingPreviewSlot,
+} from './AttachmentPreviewList';
 export type {
   AttachmentPreviewListProps,
   FileAttachmentPreviewProps,
@@ -16,6 +19,7 @@ export * from './hooks';
 export * from './icons';
 export * from './LinkPreviewList';
 export * from './MessageComposer';
+export * from './MessageComposerActions';
 export * from './MessageComposerUI';
 export * from './QuotedMessagePreview';
 export * from './SendButton';

src/components/index.ts

@@ -38,6 +38,7 @@ export * from './Notifications';
 export * from './Poll';
 export * from './Reactions';
 export * from './SafeAnchor';
+export * from './SummarizedMessagePreview';
 export * from './TextareaComposer';
 export * from './Thread';
 export * from './Threads';

src/context/index.ts

@@ -14,4 +14,5 @@ export * from './ModalContext';
 export * from './PollContext';
 export * from './TranslationContext';
 export * from './TypingContext';
+export * from './VirtualizedMessageListContext';
 export * from './WithComponents';