real-time updates on note detail view

`useNoteCapture` already subscribes to all updates for a note, so
we can tell it when a note gets replied to, too

Since I'm not actually adding any extra subscription in the client,
just an extra callback, there should be no overhead when replies are
not coming in.

Also, all the timelines already call `useNoteCapture` for each note
displayed, so we know the whole `GlobalEventService` thing works fine.

Many thanks to VueJS for taking care of all the DOM complications

packages/frontend/src/components/SkNoteSub.vue

@@ -141,6 +141,7 @@ const likeButton = shallowRef<HTMLElement>();
 
 let appearNote = computed(() => isRenote ? props.note.renote as Misskey.entities.Note : props.note);
 const defaultLike = computed(() => defaultStore.state.like ? defaultStore.state.like : null);
+const replies = ref<Misskey.entities.Note[]>([]);
 
 const isRenote = (
 	props.note.renote != null &&
@@ -149,10 +150,16 @@ const isRenote = (
 	props.note.poll == null
 );
 
+async function addReplyTo(note, replyNote: Misskey.entities.Note) {
+		replies.value.unshift(replyNote);
+}
+
 useNoteCapture({
 	rootEl: el,
 	note: appearNote,
 	isDeletedRef: isDeleted,
+	// only update replies if we are, in fact, showing replies
+	onReplyCallback: props.detail && props.depth < numberOfReplies.value ? addReplyTo : undefined,
 });
 
 if ($i) {
@@ -259,8 +266,6 @@ watch(() => props.expandAllCws, (expandAllCws) => {
 	if (expandAllCws !== showContent.value) showContent.value = expandAllCws;
 });
 
-let replies = ref<Misskey.entities.Note[]>([]);
-
 function boostVisibility() {
 	os.popupMenu([
 		{