refactor: every count in the web app is said by one plural(), with the viewer's thousands separator; a source guard names any hand-written copy (M505 #5642)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

web/src/lib/components/wanted/WantList.svelte

@@ -1,4 +1,5 @@
 <script lang="ts">
+  import { plural } from '#lib/utils/plural.js';
   import { Album, ChevronDown, ListChecks, ListMusic, Search, X } from 'lucide-svelte';
   import { useQueryClient } from '@tanstack/svelte-query';
   import { createWantsQuery, removeWant, searchWant } from '#lib/api/wanted.js';
@@ -98,8 +99,7 @@
   function arrived(w: Want): string | null {
     const g = w.grab;
     if (!g || g.import_state !== 'imported' || !g.imported_at) return null;
-    const n = g.imported_files === 1 ? '1 track' : `${g.imported_files} tracks`;
-    return `Imported ${n} ${relativeTime(g.imported_at)} from ${g.name}`;
+    return `Imported ${plural(g.imported_files, 'track', 'tracks')} ${relativeTime(g.imported_at)} from ${g.name}`;
   }
 
   // A want the schedule still searches for: open, or held but wanted for a
@@ -119,7 +119,6 @@
     return 'Its files went missing';
   }
 
-  const albums = (n: number) => (n === 1 ? '1 album' : `${n} albums`);
 
   function kind(w: Want): string {
     const parts = [w.primary_type, ...w.secondary_types].filter(Boolean);
@@ -141,7 +140,7 @@
       <a href="/collection" class="text-xs text-text-secondary hover:text-text-primary">← Catalogue</a>
       <h2 class="truncate text-xl font-medium text-text-primary">{head.artist_name}</h2>
       <p class="text-sm text-text-secondary" data-testid="catalogue-artist-counts">
-        {head.held} of {albums(head.albums)} held{head.wanted ? ` · ${head.wanted} wanted` : ''}{head.missing
+        {head.held} of {plural(head.albums, 'album', 'albums')} held{head.wanted ? ` · ${head.wanted} wanted` : ''}{head.missing
           ? ` · ${head.missing} with files missing`
           : ''}{head.downloading ? ` · ${head.downloading} downloading` : ''}
       </p>
@@ -200,7 +199,7 @@
               {a.name}
             {/if}
           </span>
-          <span class="shrink-0 text-xs text-text-muted">{albums(a.wants.length)}</span>
+          <span class="shrink-0 text-xs text-text-muted">{plural(a.wants.length, 'album', 'albums')}</span>
         </h2>{/if}
         <ul class="divide-y divide-border rounded-lg border border-border bg-surface">
           {#each a.wants as w (w.id)}