feat(contact): add toast notifications for form feedback

- Add toast notifications for contact form success/error responses
- Add toast notifications for backend errors in AppFooter
- Add accessibility explanation for honeypot field
- Add loading state to contact form submit button
- Add i18n translations for toast messages (en/fr)
- Fix honeypot input missing v-model binding

app/components/AppFooter.vue

@@ -27,6 +27,7 @@
 import type { NavigationMenuItem } from '@nuxt/ui';
 import { version } from '../../package.json';
 
+const toast = useToast();
 const { isMobile } = useDevice();
 const orientation = computed(() => (isMobile ? 'vertical' : 'horizontal'));
 const { getMeta } = useBackend();
@@ -48,4 +49,13 @@ const items = computed<NavigationMenuItem[]>(() => [
     to: 'https://rust-lang.org/',
   },
 ]);
+watch(error, (value) => {
+  if (value) {
+    toast.add({
+      title: $t('backend.errors.title'),
+      description: $t(value.message ?? 'backend.errors.unknown'),
+      color: 'error',
+    });
+  }
+});
 </script>