feat: add thread functionality to room features

- Enhance RoomInput to support sending messages as replies in threads by adding `threadRootId` prop.
- Update RoomTimeline to manage active thread state and handle opening threads.
- Implement ThreadView component to display thread messages and input.
- Create HomeThreadsCategory to list threads user has participated in.
- Introduce activeThreadIdAtomFamily to manage active thread state across rooms.

src/app/components/message/Reply.tsx

@@ -58,6 +58,8 @@ type ReplyProps = {
   replyEventId: string;
   threadRootId?: string | undefined;
   onClick?: MouseEventHandler | undefined;
+  /** Called when the thread indicator badge is clicked. Receives the thread root event ID. */
+  onOpenThread?: (threadRootId: string) => void;
   getMemberPowerTag?: GetMemberPowerTag;
   accessibleTagColors?: Map<string, string>;
   legacyUsernameColor?: boolean;
@@ -71,6 +73,7 @@ export const Reply = as<'div', ReplyProps>(
       replyEventId,
       threadRootId,
       onClick,
+      onOpenThread,
       getMemberPowerTag,
       accessibleTagColors,
       legacyUsernameColor,
@@ -107,7 +110,11 @@ export const Reply = as<'div', ReplyProps>(
     return (
       <Box direction="Row" gap="200" alignItems="Center" {...props} ref={ref}>
         {threadRootId && (
-          <ThreadIndicator as="button" data-event-id={threadRootId} onClick={onClick} />
+          <ThreadIndicator
+            as="button"
+            data-event-id={threadRootId}
+            onClick={onOpenThread ? () => onOpenThread(threadRootId) : onClick}
+          />
         )}
         <ReplyLayout
           as="button"