refactor: remove old chat components and implement new sidebar structure

- Deleted `chats-client.tsx` and `page.tsx` as part of the chat management overhaul.
- Introduced `AllChatsSidebar` and `NavChats` components for improved chat navigation and management.
- Updated sidebar to integrate new chat components and removed the deprecated `NavProjects`.
- Enhanced chat deletion handling and added loading states for better user experience.
- Added new translation keys for chat-related UI strings.

surfsense_web/messages/zh.json

@@ -642,6 +642,13 @@
 		"no_chats_found": "未找到对话",
 		"no_recent_chats": "暂无最近对话",
 		"view_all_chats": "查看所有对话",
+		"all_chats": "所有对话",
+		"all_chats_description": "浏览和管理您的所有对话",
+		"no_chats": "暂无对话",
+		"start_new_chat_hint": "从研究员开始新对话",
+		"error_loading_chats": "加载对话时出错",
+		"chat_deleted": "对话删除成功",
+		"error_deleting_chat": "删除对话失败",
 		"search_space": "搜索空间",
 		"notes": "笔记",
 		"all_notes": "所有笔记",