fix: add missing error handling for sendMessage promise rejections

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

memento-note/components/ai-chat.tsx

@@ -83,19 +83,24 @@ export function AIChat({ showFloatingTrigger = true }: { showFloatingTrigger?: b
       }
     }
 
-    await sendMessage(
-      { text },
-      {
-        body: {
-          tone: selectedTone,
-          chatScope,
-          notebookId: chatScope !== 'all' ? chatScope : undefined,
-          webSearch: webSearch && webSearchAvailable,
-          conversationId: convId,
-          language,
+    try {
+      await sendMessage(
+        { text },
+        {
+          body: {
+            tone: selectedTone,
+            chatScope,
+            notebookId: chatScope !== 'all' ? chatScope : undefined,
+            webSearch: webSearch && webSearchAvailable,
+            conversationId: convId,
+            language,
+          }
         }
-      }
-    )
+      )
+    } catch (error) {
+      console.error('Chat send error:', error)
+      toast.error(t('chat.assistantError') || 'Failed to send message')
+    }
   }
 
   const fetchHistory = async () => {