feat: admin Suspect sources report, for files named like video rips (#5410)

Humanz turned out to be YouTube rips: "(Official Video)", "Visualizer", a
reaction video filed as a song, junk disc numbers (#5401). The library holds
about 200 more files named the same way. This report lists them, grouped by
folder like Missing files, with the markers each file name carries.

- GET /api/admin/library/suspect-sources: one marker list in Go builds both
  the Postgres ~* filter and each row's labels, so they cannot drift.
  Basename only; missing files are left out.
- Markers calibrated on the live library: "live in/at" dropped (real live
  albums), "reaction" narrowed (it caught "Chain Reaction").
- Admin tab "Suspect sources", read-only, loads as you scroll; a folder split
  across pages is joined back into one.

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

web/src/lib/components/AdminTabs.svelte

@@ -10,6 +10,7 @@
     { href: '/admin/quarantine',      label: 'Quarantine'      },
     { href: '/admin/missing-files',   label: 'Missing files'   },
     { href: '/admin/duplicates',      label: 'Duplicates'      },
+    { href: '/admin/suspect-sources', label: 'Suspect sources' },
     { href: '/admin/playback-errors', label: 'Playback errors' },
     { href: '/admin/diagnostics',     label: 'Diagnostics'     },
     { href: '/admin/tuning',          label: 'Tuning'          },

web/src/lib/components/AdminTabs.test.ts

@@ -52,7 +52,7 @@ describe('AdminTabs', () => {
     );
   });
 
-  test('renders all ten tabs in order', () => {
+  test('renders all eleven tabs in order', () => {
     state.pageUrl = new URL('http://localhost/admin');
     render(AdminTabs);
     const links = screen.getAllByRole('link');
@@ -67,6 +67,9 @@ describe('AdminTabs', () => {
       // Duplicates follows Missing files: both are library-health reports on
       // what the library holds, rather than a queue of user reports.
       'Duplicates',
+      // Suspect sources is the third library-health report: files whose
+      // names say they were ripped from a video.
+      'Suspect sources',
       'Playback errors',
       'Diagnostics',
       'Tuning',