优化: CR-08 i18n batch2全量(ProjectDetail5处+TaskDetail16key+AiChat3处+store error fallback 23处+useAiSend 3处)+@/i18n路径统一+vite别名

src/i18n/en/aiChat.ts

@@ -60,5 +60,8 @@ export default {
 
     // ── Confirm dialog ──
     confirmDeleteConversation: 'Delete chat "{title}"? This cannot be undone.',
+    clearChat: 'Clear',
+    confirmClearChat: 'Are you sure you want to clear all messages in this chat? This cannot be undone.',
+    toastSendFail: 'Send failed: {msg}',
   },
 }