[core] Fix notifications dismiss function

src/components/Notification.vue

@@ -6,7 +6,6 @@
     @click="click"
   >
     <q-btn
-      v-if="modelValue.accept !== undefined"
       round
       dense
       icon="mdi-trash-can"
@@ -14,7 +13,7 @@
       color="negative"
       class="q-ma-xs"
       title="Löschen"
-      style="position: absolute; top: 0; right: 0"
+      style="position: absolute; top: 0; right: 0; z-index: 999"
       @click="dismiss"
     />
     <q-card-section class="q-pa-xs">