fix(chat): support unarchive toggle and dynamic toast in chat header menu (#31473) (#31857)

- Pass `archived` state from active chat model to Navbar context menu
- Render 'Unarchive' instead of 'Archive' when `chat?.archived` is true in Navbar/Menu.svelte
- Dynamically display 'Chat unarchived.' toast upon unarchiving in archiveChatHandler
- Closes #31473

Co-authored-by: PINYO PATTANAWASANPORN <pattanawasanporn@gmail.com>

src/lib/components/chat/Chat.svelte

@@ -4209,12 +4209,12 @@
 
 	const archiveChatHandler = async (id: string) => {
 		try {
-			await archiveChatById(localStorage.token, id);
+			const res = await archiveChatById(localStorage.token, id);
 			initNewChat();
 			await goto('/');
 			await refreshChatList(localStorage.token, { refreshPinned: true });
 			await refreshFolderChatLists();
-			toast.success($i18n.t('Chat archived.'));
+			toast.success(res?.archived ? $i18n.t('Chat archived.') : $i18n.t('Chat unarchived.'));
 		} catch (error) {
 			console.error('Error archiving chat:', error);
 			toast.error($i18n.t('Failed to archive chat.'));
@@ -4422,6 +4422,7 @@
 							{readOnly}
 							chat={{
 								id: $chatId,
+								archived: chat?.archived ?? false,
 								chat: {
 									title: $chatTitle,
 									models: selectedModels,

src/lib/components/layout/Navbar/Menu.svelte

@@ -484,7 +484,9 @@
 					}}
 				>
 					<ArchiveBox className="size-3.5" strokeWidth="1.5" />
-					<div class="flex items-center">{$i18n.t('Archive')}</div>
+					<div class="flex items-center">
+						{chat?.archived ? $i18n.t('Unarchive') : $i18n.t('Archive')}
+					</div>
 				</button>
 
 				{#if $user?.role === 'admin' || ($user?.permissions?.chat?.delete ?? true)}