feat(dashboard): red-dot weak-point map on /defects (T7)

Overlay each filed defect as a red dot inside its section box with a
diagonal date label; cap visible dots and collapse the remainder to a
"+N more" using the authoritative per-section counts (T6).

Add an `overlay` scoped slot to BoardView (C2) so the dashboard can layer
dots without forking the board definition (F1); the reporting view leaves
it empty. DotMap groups the bounded feed by section and the /defects page
wires both endpoints.

app/pages/defects.vue

@@ -1,6 +1,23 @@
 <script setup lang="ts">
 // Defect-viewing route (`/defects`) — the read-only board with the weak-point
 // map and feed. Same domain as reporting (ADR 0004).
+import { sections } from '~/board/definition'
+
+interface DefectView {
+  id: string
+  sectionId: string
+  createdAt: string
+}
+
+// Fetch enough of the feed to fill every section's dot cap, plus the
+// authoritative per-section totals that drive each "+N more" (T6).
+const { data: defects } = await useFetch<DefectView[]>('/api/defects', {
+  query: { limit: sections.length * 12 },
+  default: () => [],
+})
+const { data: counts } = await useFetch<Record<string, number>>('/api/defects/counts', {
+  default: () => ({}),
+})
 </script>
 
 <template>
@@ -10,8 +27,8 @@
       <p class="opacity-70">Every defect filed on the board.</p>
     </header>
 
-    <BoardView />
+    <DotMap :defects="defects" :counts="counts" />
 
-    <p class="opacity-60">The red-dot map (T7) and defect feed (T8) land next.</p>
+    <p class="opacity-60">The defect feed and verbatim modal (T8) land next.</p>
   </main>
 </template>