refactor(fe): P3 pages standardize to screen-type v2 templates

Refactored 4 feature pages to use standard screen-type v2 layouts:

1. HomePage → ScorecardDashboardPage
   - Exception-driven work queue metrics + dashboard layout
   - KPI cards, filters, operational guides
   - Viewport-fit ready, no page-level scrolling

2. ModelsList → MasterDetailCrudPage
   - Master list + detail panel layout
   - Model grid with phase/performance metrics
   - Search, filter, pagination

3. ModelDetail → DetailReadPage
   - Read-only model detail view
   - State management (LOADING/ERROR/READY)
   - Metric display (PBO, DSR, Return)

4. ShadowRunDetail → DetailReadPage
   - Shadow run detail view
   - State management (LOADING/ERROR/READY)
   - Performance metrics (PBO, DSR, OOS)

Pattern Applied:
- Remove PageLayout, use screen-type component
- Add StandardScreenProps (state, evidence)
- State computed from query status
- Slot structure maintained or aligned
- No functional changes, pure standardization

Benefits:
- Consistent layout across pages
- Standardized state management
- Improved viewport-fit compliance
- Better component reusability

Next: Viewport-fit final validation + viewport-fit edge cases

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

frontend/src/features/shadow-run/pages/ShadowRunDetail.vue

@@ -1,8 +1,10 @@
 <script setup lang="ts">
 import { computed } from 'vue'
 import { useRoute } from 'vue-router'
+import { DetailReadPage } from '../../../shared/ui/screen-types/v2'
 import { SkeletonLoader } from '../../../shared/ui/components'
 import { useShadowRunDetail } from '../composables/useShadowRuns'
+import type { StandardScreenProps } from '../../../shared/ui/contracts/screenContract'
 
 const route = useRoute()
 
@@ -11,10 +13,22 @@ const runId = computed(() => route.params.runId as string)
 const shadowRunQuery = useShadowRunDetail(runId.value)
 
 const run = computed(() => shadowRunQuery.data as any)
+
+const screenState = computed<StandardScreenProps['state']>(() => {
+  if (shadowRunQuery.isPending) return 'LOADING'
+  if (shadowRunQuery.isError) return 'ERROR'
+  return 'READY'
+})
+const screenEvidence = { asOf: new Date().toISOString(), version: '1.0' }
 </script>
 
 <template>
-  <div class="shadow-run-detail-page">
+  <DetailReadPage
+    :title="`Shadow Run #${runId}`"
+    :state="screenState"
+    :evidence="screenEvidence"
+  >
+    <template #primary>
     <header class="page-header">
       <h1>Shadow Run Details</h1>
     </header>
@@ -57,7 +71,8 @@ const run = computed(() => shadowRunQuery.data as any)
         </div>
       </div>
     </div>
-  </div>
+    </template>
+  </DetailReadPage>
 </template>
 
 <style scoped>