fix: add missing error handling for sendMessage promise rejections

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

memento-note/components/chat/chat-container.tsx

@@ -137,17 +137,22 @@ export function ChatContainer({ initialConversations, notebooks, webSearchAvaila
       }
     }
 
-    await sendMessage(
-      { text: content },
-      {
-        body: {
-          conversationId: convId,
-          notebookId: notebookId || selectedNotebook || undefined,
-          language,
-          webSearch: webSearchEnabled,
-        },
-      }
-    )
+    try {
+      await sendMessage(
+        { text: content },
+        {
+          body: {
+            conversationId: convId,
+            notebookId: notebookId || selectedNotebook || undefined,
+            language,
+            webSearch: webSearchEnabled,
+          },
+        }
+      )
+    } catch (error) {
+      console.error('Chat send error:', error)
+      toast.error(t('chat.assistantError') || 'Failed to send message')
+    }
   }
 
   const handleNewChat = () => {