feat(settings): tidy Maintenance tab into compact tiles + center the views (pass 2)

Goal (operator 2026-06-18): the overview of a Settings tab fits one unscrolled
viewport; expanding a tile to read into it is the only reason to scroll.

- Every Maintenance card converted to the collapsible MaintenanceTile (collapsed
  by default = icon + short title + one-line blurb). Task cards (ML backfill,
  centroids, thumbnails, archive re-extract, missing-file repair, DB maintenance)
  sit in a responsive grid; running tasks auto-expand. Tagging config (suggestion
  thresholds, allowlist, aliases) grouped in one Tagging section as collapsible
  tiles; Backup is its own collapsible tile.
- Three labeled sections mirror the Cleanup tab: Backfills and reprocessing /
  Tagging / Storage.
- Center the whole Settings surface: SettingsView is now a centered, width-capped
  (1140px) column so the tab strip and every panel sit in a tidy centered measure
  (was full-width). CleanupView drops its own left-aligned max-width to fill it.

All card logic unchanged - only the chrome.

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

frontend/src/components/settings/AliasTable.vue

@@ -1,6 +1,9 @@
 <template>
-  <v-card>
-    <v-card-title>Tag aliases ({{ store.rows.length }})</v-card-title>
+  <MaintenanceTile
+    icon="mdi-tag-arrow-right-outline"
+    :title="`Tag aliases (${store.rows.length})`"
+    blurb="Alternate tag spellings that map to a canonical tag."
+  >
     <v-data-table-virtual
       :headers="headers" :items="store.rows" :loading="store.loading"
       height="360" density="compact"
@@ -18,12 +21,13 @@
         />
       </template>
     </v-data-table-virtual>
-  </v-card>
+  </MaintenanceTile>
 </template>
 
 <script setup>
 import { onMounted } from 'vue'
 import { useAliasesStore } from '../../stores/aliases.js'
+import MaintenanceTile from '../common/MaintenanceTile.vue'
 
 const store = useAliasesStore()
 const headers = [