refactor: simplify page models and view driver usage

Move simple page models into page components and build trivial computed
models directly in views to avoid unnecessary page drivers. Update views
to destructure page driver returns and rely on template ref unwrapping,
and document the guidance for when page drivers should be introduced.refactor: simplify page models and view driver usage

Move simple page models into page components and build trivial computed
models directly in views to avoid unnecessary page drivers. Update views
to destructure page driver returns and rely on template ref unwrapping,
and document the guidance for when page drivers should be introduced.

src/views/demos/SectionFormPageDemo.vue

@@ -2,16 +2,15 @@
 import PageSectionFormPageDemo from '@/components/pages/PageSectionFormPageDemo.vue'
 import { useSectionsDemoPage } from '@/composables/page-drivers/useSectionsDemoPage'
 
-// Demo view 維持薄層，只掛 page driver，並把 page model / actions 傳給 page component。
-const page = useSectionsDemoPage()
+const { demoForm, handleFormBack, handleFormSubmit, pageModel, resetDemoForm } = useSectionsDemoPage()
 </script>
 
 <template>
   <PageSectionFormPageDemo
-    v-model:demo-form="page.demoForm.value"
-    :page="page.pageModel.value"
-    @back="page.handleFormBack"
-    @reset="page.resetDemoForm"
-    @submit="page.handleFormSubmit"
+    v-model:demo-form="demoForm"
+    :page="pageModel"
+    @back="handleFormBack"
+    @reset="resetDemoForm"
+    @submit="handleFormSubmit"
   />
 </template>