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/api/admin.ts

@@ -1,9 +1,10 @@
-import { createQuery } from '@tanstack/svelte-query';
+import { createInfiniteQuery, createQuery } from '@tanstack/svelte-query';
 import { api } from './client';
 import { qk } from './queries';
 import type {
   ActionResult,
   AdminMissingResponse,
+  AdminSuspectResponse,
   AdminDuplicatesResponse,
   MergeDuplicateResult,
   AdminPlaybackError,
@@ -896,6 +897,34 @@ export function createMissingFilesQuery(offset: number = 0, limit: number = 50)
   });
 }
 
+// Suspect sources (#5410) --------------------------------------------------
+
+export const SUSPECT_SOURCES_PAGE_SIZE = 50;
+
+export async function listSuspectSources(offset: number = 0): Promise<AdminSuspectResponse> {
+  return api.get<AdminSuspectResponse>(
+    `/api/admin/library/suspect-sources?limit=${SUSPECT_SOURCES_PAGE_SIZE}&offset=${offset}`
+  );
+}
+
+// The next offset counts tracks, not groups: limit and total are in tracks.
+export function suspectSourcesNextOffset(last: AdminSuspectResponse): number | undefined {
+  const loaded = last.offset + last.groups.reduce((n, g) => n + g.tracks.length, 0);
+  return loaded >= last.total ? undefined : loaded;
+}
+
+// Loads as the page scrolls (rule 172). Changes only when files are added or
+// removed, so it is not re-fetched on every focus.
+export function createSuspectSourcesQuery() {
+  return createInfiniteQuery({
+    queryKey: qk.adminSuspectSources(),
+    queryFn: ({ pageParam }) => listSuspectSources(pageParam as number),
+    initialPageParam: 0,
+    getNextPageParam: suspectSourcesNextOffset,
+    staleTime: 120_000
+  });
+}
+
 // Missing-file re-acquisition (#2527 / milestone #290) ----------------------
 
 export type ReacquisitionSettings = {

web/src/lib/api/queries.ts

@@ -58,6 +58,7 @@ export const qk = {
     ['adminMissingFiles', { offset: offset ?? 0 }] as const,
   adminDuplicates:        (offset?: number) =>
     ['adminDuplicates', { offset: offset ?? 0 }] as const,
+  adminSuspectSources:    () => ['adminSuspectSources'] as const,
   adminDiagnosticDevices: (userId?: string) =>
     ['adminDiagnosticDevices', { userId: userId ?? 'all' }] as const,
   smtpConfig:             ()              => ['smtpConfig'] as const,

web/src/lib/api/types.ts

@@ -419,6 +419,37 @@ export type AdminMissingResponse = {
   groups: AdminMissingGroup[];
 };
 
+// Suspect sources (#5410) --------------------------------------------------
+
+// A present track whose filename carries a video-rip marker. markers are the
+// reasons, read from the file's basename: "music video", "[Audio]", "MV"...
+export type AdminSuspectTrack = {
+  track_id: string;
+  title: string;
+  artist_id: string;
+  artist_name: string;
+  album_id: string;
+  album_title: string;
+  file_path: string;
+  duration_sec: number;
+  disc_number: number | null;
+  track_number: number | null;
+  markers: string[];
+};
+
+// A folder's worth of flagged tracks; the server orders and groups by folder.
+export type AdminSuspectGroup = {
+  directory: string;
+  tracks: AdminSuspectTrack[];
+};
+
+export type AdminSuspectResponse = {
+  total: number;
+  limit: number;
+  offset: number;
+  groups: AdminSuspectGroup[];
+};
+
 // Duplicates report (#3912) -------------------------------------------------
 
 // One copy in a proposed duplicate group. like_count and play_count cover every