chore: 修复大量导入路径错误

- 迁移 files API 到 shared/api/
- 修复所有 features 中的 @/api/ 导入
- 修复所有 features 中的 @/composables/ 导入
- 更新 useOrderDetail 中的 uploadFile 调用

类型错误：272 → 190 → 135

frontend/src/features/chats/views/ChatView.vue

@@ -10,10 +10,10 @@ import {
   sendChatMessage,
   type ChatConversation,
   type ChatMessage,
-} from '@/api/chats'
+} from '@/features/chats/api/chats'
 import { uploadFile } from '@/shared/api/files'
 import ChatAttachmentImage from '@/components/ChatAttachmentImage.vue'
-import { useChatSSE, type ChatEvent } from '@/composables/useChatSSE'
+import { useChatSSE, type ChatEvent } from '@/features/chats/composables/useChatSSE'
 import { formatDateMinute } from '@/utils/time'
 
 const currentUserId = Number(localStorage.getItem('user_id') || 0)