🚸(frontend) add toast error when AI request fails

When the AI request fails, a toast error is
displayed to the user.

src/frontend/apps/impress/src/features/docs/doc-editor/components/AIButton.tsx

@@ -374,6 +374,7 @@ const useHandleAIError = () => {
         });
       }
 
+      toast(t('AI seems busy! Please try again.'), VariantType.ERROR);
       console.error(error);
     },
     [toast, t],

src/frontend/apps/impress/src/i18n/translations.json

@@ -5,6 +5,7 @@
       "\"{{email}}\" is already invited to the document.": "\"{{email}}\" est déjà invité à accéder au document.",
       "\"{{email}}\" is already member of the document.": "\"{{email}}\" est déjà membre du document.",
       "AI Actions": "Actions IA",
+      "AI seems busy! Please try again.": "L'IA semble occupée ! Veuillez réessayer.",
       "Accessibility": "Accessibilité",
       "Accessibility statement": "Déclaration d'accessibilité",
       "Address:": "Adresse :",