refactor(ui): CardHeading primitive for icon+title card/dialog headings (DRY pattern sweep)

The icon+title v-card-title heading (d-flex align-center + gap + <v-icon size=small> +
<span>) was hand-rolled identically in 13 cards/dialogs (15 heading instances).
Consolidate to <CardHeading icon title> (components/common) with an iconColor
prop (error headings) and a default slot for trailing content (spacer+actions,
inline status chip). Adopted everywhere the pattern appears — all-or-nothing per
the hardened DRY process.

Over-DRY guard: plain text-only <v-card-title> one-liners are NOT this pattern
and stay; DownloadDetailModal leads with a status CHIP (not an icon), a different
concept, left alone. §8b: the only remaining d-flex align-center v-card-title is
that intentional variant. Catalog updated.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

frontend/src/components/settings/ImportTaskList.vue

@@ -1,7 +1,6 @@
 <template>
   <v-card>
-    <v-card-title class="d-flex align-center" style="gap: 12px;">
-      <span>Recent import tasks</span>
+    <CardHeading title="Recent import tasks">
       <v-spacer />
       <v-select
         v-model="statusFilter" :items="statusOptions" density="compact"
@@ -29,7 +28,7 @@
       >
         Clear completed…
       </v-btn>
-    </v-card-title>
+    </CardHeading>
     <v-data-table-virtual
       :headers="headers" :items="store.tasks" :loading="store.tasksLoading"
       height="480" density="compact" no-data-text="No tasks yet — trigger a scan above."
@@ -129,6 +128,7 @@ import { toast } from '../../utils/toast.js'
 import { computed, ref } from 'vue'
 import { useImportStore } from '../../stores/import.js'
 import ErrorDetailModal from '../common/ErrorDetailModal.vue'
+import CardHeading from '../common/CardHeading.vue'
 
 const store = useImportStore()
 const statusFilter = ref(null)