feat(ia): wave 1 — Import tab dissolves, Maintenance regroups by system, one extension home

Settings IA per the approved A3 design (the old layout was the two-app merge
fossilized):
- Import tab retired: ImportTriggerPanel + ImportTaskList deleted (manual
  /import scans stay API-level; imports arrive via downloads/extension, heal
  via the Layer-2 auto-refetch sweep, and show in Activity). ImportFiltersForm
  moves to Maintenance → 'Ingestion & filters' and loads its own settings; the
  import store shrinks to settings-only (no remaining consumers of the
  scan/task-list machinery). Overview's pending banner now points at Activity.
- Maintenance regrouped: Ingestion & filters / GPU agent & embeddings
  (GpuAgent, Failed processing, CPU embedding backfill) / Tagging (sliders,
  Heads, Aliases) / Library health (MissingFiles, Thumbnails, DB, Archive
  re-extract demoted last) / Storage.
- One extension home: BrowserExtensionCard moves from Settings → Overview to
  Subscriptions → Settings, above the API key bar it authenticates.
- Single-color import filter WIRED: skip_single_color/threshold existed since
  FC-2 but nothing read them (the audit module's docstring said as much) —
  now enforced on both import paths via the audit's canonical predicate
  (tolerance 30, matching the Cleanup card default; animated images exempt
  like the transparency check). Default stays off; test added.
- Dead weight: PlaceholderView (zero refs) and the permanently-disabled
  'Export failed logs (CSV — v2)' menu stub deleted; stale docs fixed
  (celery queue docstring, threshold comment citing retired tasks, ml
  package docstring, HeadsCard 'replaces Camie' blurb).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CDgx8bQS5YrGRK76v8HUnM

frontend/src/components/settings/MaintenancePanel.vue

@@ -1,36 +1,59 @@
 <template>
   <div class="fc-maint">
     <p class="fc-muted text-body-2 mb-5">
-      One-off backfills, tagging config and storage tools. Heads train nightly
-      and auto-apply earned tags. Click a tile to open it.
+      Processing, tagging and storage tools, grouped by system. Heads train
+      nightly and auto-apply earned tags. Click a tile to open it.
     </p>
 
     <section class="fc-section">
-      <h3 class="fc-section__title">Backfills &amp; reprocessing</h3>
-      <p class="fc-section__hint">Re-run tagging, thumbnails, extraction and DB upkeep.</p>
-      <div class="fc-tile-grid">
-        <MLBackfillCard />
-        <ThumbnailBackfillCard />
-        <ArchiveReextractCard />
-        <MissingFileRepairCard />
+      <h3 class="fc-section__title">Ingestion &amp; filters</h3>
+      <p class="fc-section__hint">
+        What gets imported — dedup sensitivity, size/transparency/solid-color
+        filters. Applies to downloads and folder imports alike.
+      </p>
+      <div class="fc-tile-stack">
+        <ImportFiltersForm />
+      </div>
+    </section>
+
+    <section class="fc-section">
+      <h3 class="fc-section__title">GPU agent &amp; embeddings</h3>
+      <p class="fc-section__hint">
+        The desktop agent that does the heavy lifting, its failure triage, and
+        the CPU fallback.
+      </p>
+      <div class="fc-tile-stack">
+        <GpuAgentCard />
         <GpuTriageCard />
-        <DbMaintenanceCard />
+        <MLBackfillCard />
       </div>
     </section>
 
     <section class="fc-section">
       <h3 class="fc-section__title">Tagging</h3>
       <p class="fc-section__hint">
-        Suggestion thresholds, the auto-apply allowlist and tag aliases.
+        Suggestion thresholds, trained heads and tag aliases.
       </p>
       <div class="fc-tile-stack">
         <MLThresholdSliders />
         <HeadsCard />
-        <GpuAgentCard />
         <AliasTable />
       </div>
     </section>
 
+    <section class="fc-section">
+      <h3 class="fc-section__title">Library health</h3>
+      <p class="fc-section__hint">
+        Self-healing and repair: missing files, thumbnails, database upkeep.
+      </p>
+      <div class="fc-tile-grid">
+        <MissingFileRepairCard />
+        <ThumbnailBackfillCard />
+        <DbMaintenanceCard />
+        <ArchiveReextractCard />
+      </div>
+    </section>
+
     <section class="fc-section">
       <h3 class="fc-section__title">Storage</h3>
       <p class="fc-section__hint">Database + image backups and restore.</p>
@@ -44,6 +67,7 @@
 <script setup>
 import { onMounted, onUnmounted } from 'vue'
 
+import ImportFiltersForm from './ImportFiltersForm.vue'
 import MLBackfillCard from './MLBackfillCard.vue'
 import ThumbnailBackfillCard from './ThumbnailBackfillCard.vue'
 import ArchiveReextractCard from './ArchiveReextractCard.vue'