refactor: replace nuxt-page with slot in layout components

- Updated layout files (default.vue, empty.vue, simple-centered.vue) to replace the nuxt-page component with a slot for improved flexibility in content rendering.

Author: tacxou

apps/web/src/layouts/default.vue

@@ -3,7 +3,7 @@ q-layout(view="hHh LpR lff" style="margin-top: -1px;")
   sesame-layouts-default-appbar
   sesame-layouts-default-drawer
   q-page-container.full-height
-    nuxt-page
+    slot
     q-dialog(seamless v-model="eventSeamless" position="bottom")
       q-card(style="width: 350px")
         q-linear-progress(:value="eventSeamlessProgress" color="amber-9")

apps/web/src/layouts/empty.vue

@@ -1,7 +1,7 @@
 <template lang="pug">
 q-layout(view="hHh LpR lff" style="margin-top: -1px;")
   q-page-container
-    nuxt-page
+    slot
 </template>
 
 <script lang="ts">

apps/web/src/layouts/simple-centered.vue

@@ -4,7 +4,7 @@ q-layout(view="lHh Lpr fff")
     q-page.window-height.window-width.row.justify-center.items-center(
       :style-fn="getStyle"
     )
-      nuxt-page
+      slot
       q-fab.absolute(
         style="bottom: 16px; right: 16px;"
         color="primary"