feat(settings): tidy Cleanup tab into sectioned compact tiles (pass 1)

The Cleanup + Maintenance sections had ~17 full-width stacked cards with long
descriptions — a hunt to scan. Operator wants compact, sectioned, scannable tiles
(2026-06-18: keep both tabs, group inside, compact tiles in a grid).

New common/MaintenanceTile.vue: a compact expandable tile (icon + short title +
one-line blurb collapsed; click the header to expand the full controls/preview/
result inline; keyboard-accessible button + focus ring;  tints the
icon,  keeps a running task expanded).

Cleanup tab (this pass) restructured into 3 sections — Import-filter audits
(Min dimensions, Transparency, Single-color) / Duplicates & posts (Bare posts,
Duplicate posts, Deduplicate videos, Gated-post previews) / Tags (Unused, Legacy,
Reset content tagging, Standardize casing) — each a responsive grid of tiles.
PostMaintenanceCard split into 2 tiles, TagMaintenanceCard into 4. Moved
VideoDedupCard + GatedPurgeCard from the Maintenance tab here (both are
destructive content cleanup). All card logic unchanged — only the chrome.

Maintenance tab tiling is pass 2 (TODO noted in MaintenancePanel).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/src/components/settings/VideoDedupCard.vue

@@ -3,54 +3,57 @@
        duration + aspect (the same clip re-encoded / pulled from multiple
        sources). Preview first, then apply (destructive: removes the redundant
        copies, keeping the highest-resolution one). -->
-  <v-card>
-    <v-card-title>Deduplicate videos</v-card-title>
-    <v-card-text>
-      <p class="text-body-2 mb-3">
-        Finds videos of the same artist that are the same content across
-        re-encodes (matching duration + aspect ratio) and keeps the
-        highest-resolution copy. <strong>Preview</strong> first to see what would
-        be removed; <strong>Apply</strong> re-points each post to the kept copy,
-        then deletes the redundant videos and their files. The first run also
-        computes durations for older videos, so it may take a while.
-      </p>
+  <MaintenanceTile
+    icon="mdi-content-duplicate"
+    title="Deduplicate videos"
+    blurb="Collapse re-encoded duplicate videos, keeping the best copy."
+    destructive
+    :open="applying || previewing"
+  >
+    <p class="text-body-2 mb-3">
+      Finds videos of the same artist that are the same content across
+      re-encodes (matching duration + aspect ratio) and keeps the
+      highest-resolution copy. <strong>Preview</strong> first to see what would
+      be removed; <strong>Apply</strong> re-points each post to the kept copy,
+      then deletes the redundant videos and their files. The first run also
+      computes durations for older videos, so it may take a while.
+    </p>
 
-      <div class="d-flex align-center flex-wrap" style="gap: 12px;">
-        <v-btn
-          color="primary" variant="tonal" rounded="pill"
-          :loading="previewing" :disabled="applying" @click="preview"
-        >
-          <v-icon start>mdi-magnify</v-icon> Preview
-        </v-btn>
-        <v-btn
-          color="error" rounded="pill"
-          :loading="applying"
-          :disabled="previewing || !canApply"
-          @click="confirmOpen = true"
-        >
-          <v-icon start>mdi-content-duplicate</v-icon> Apply
-        </v-btn>
-      </div>
-
-      <v-alert
-        v-if="summary" :type="summaryType" variant="tonal" class="mt-4"
-        density="comfortable"
+    <div class="d-flex align-center flex-wrap" style="gap: 12px;">
+      <v-btn
+        color="primary" variant="tonal" rounded="pill"
+        :loading="previewing" :disabled="applying" @click="preview"
       >
-        <span v-if="applied">
-          Removed {{ summary.deleted }} redundant video(s) across
-          {{ summary.groups }} group(s); re-pointed {{ summary.relinked_posts }}
-          post link(s); reclaimed {{ humanBytes(summary.reclaim_bytes) }}.
-        </span>
-        <span v-else-if="summary.redundant > 0">
-          {{ summary.redundant }} redundant video(s) across {{ summary.groups }}
-          group(s) — {{ humanBytes(summary.reclaim_bytes) }} reclaimable. Click
-          <strong>Apply</strong> to remove them (keeping the best copy).
-        </span>
-        <span v-else>No duplicate videos found.</span>
-      </v-alert>
+        <v-icon start>mdi-magnify</v-icon> Preview
+      </v-btn>
+      <v-btn
+        color="error" rounded="pill"
+        :loading="applying"
+        :disabled="previewing || !canApply"
+        @click="confirmOpen = true"
+      >
+        <v-icon start>mdi-content-duplicate</v-icon> Apply
+      </v-btn>
+    </div>
 
-      <QueueStatusBar queue="maintenance_long" queue-label="Maintenance" />
-    </v-card-text>
+    <v-alert
+      v-if="summary" :type="summaryType" variant="tonal" class="mt-4"
+      density="comfortable"
+    >
+      <span v-if="applied">
+        Removed {{ summary.deleted }} redundant video(s) across
+        {{ summary.groups }} group(s); re-pointed {{ summary.relinked_posts }}
+        post link(s); reclaimed {{ humanBytes(summary.reclaim_bytes) }}.
+      </span>
+      <span v-else-if="summary.redundant > 0">
+        {{ summary.redundant }} redundant video(s) across {{ summary.groups }}
+        group(s) — {{ humanBytes(summary.reclaim_bytes) }} reclaimable. Click
+        <strong>Apply</strong> to remove them (keeping the best copy).
+      </span>
+      <span v-else>No duplicate videos found.</span>
+    </v-alert>
+
+    <QueueStatusBar queue="maintenance_long" queue-label="Maintenance" />
 
     <v-dialog v-model="confirmOpen" max-width="440">
       <v-card>
@@ -68,13 +71,14 @@
         </v-card-actions>
       </v-card>
     </v-dialog>
-  </v-card>
+  </MaintenanceTile>
 </template>
 
 <script setup>
 import { computed, ref } from 'vue'
 
 import { useMaintenanceTask } from '../../composables/useMaintenanceTask.js'
+import MaintenanceTile from '../common/MaintenanceTile.vue'
 import QueueStatusBar from './QueueStatusBar.vue'
 
 const confirmOpen = ref(false)