feat(defects): file a defect via a board-section modal (T5)

POST /api/defects validates the body with arktype (known section, uuid
project, non-empty trimmed verbatim) and resolves the reporter through a dev
seam (getReporter, ADR 0002) until OAuth lands. DefectForm is a DaisyUI modal
opened by a section click — pick a project, describe the problem, submit.

app/pages/index.vue

@@ -1,13 +1,33 @@
 <script setup lang="ts">
-const selected = ref<string | null>(null)
+// Andon reporting view (F2): the board is the entry point — clicking a section
+// opens the defect form for it.
+const selectedSectionId = ref<string | null>(null)
+const confirmation = ref<string | null>(null)
+
+function onFiled() {
+  selectedSectionId.value = null
+  confirmation.value = 'Thanks — your report was filed.'
+  setTimeout(() => (confirmation.value = null), 4000)
+}
 </script>
 
 <template>
-  <main>
-    <h1>Andon — report a board problem</h1>
-    <BoardView @select="(id) => (selected = id)" />
-    <p v-if="selected">
-      Selected section: <code>{{ selected }}</code> — the defect form arrives in Task 5.
-    </p>
+  <main class="mx-auto flex max-w-5xl flex-col items-center gap-6 p-6">
+    <header class="text-center">
+      <h1>Andon — report a board problem</h1>
+      <p class="opacity-70">Click a section to report a problem.</p>
+    </header>
+
+    <BoardView @select="(id) => (selectedSectionId = id)" />
+
+    <DefectForm
+      :section-id="selectedSectionId"
+      @close="selectedSectionId = null"
+      @filed="onFiled"
+    />
+
+    <div v-if="confirmation" class="toast toast-end">
+      <div class="alert alert-success">{{ confirmation }}</div>
+    </div>
   </main>
 </template>