feat: indexers and download clients you add and configure (M502 #5518)

Admin → Integrations gains "Indexers and download clients": two lists of
connections the operator adds, Fabled Librarian's model. Nothing is seeded
or copied from Lidarr.

- Indexers: Prowlarr (its native /api/v1/search, which asks every indexer
  at once; Prowlarr has no aggregate Torznab feed) and any Torznab feed.
- Download clients: qBittorrent (WebUI v2, with re-login on an expired
  session) and FabledExchange, one entry with a switch per job:
  downloads (/api/downloads), search (/api/search) and release details
  (/api/torrents/{infohash}). All three start on; its key is optional.
- Each entry: enable, name, address, a write-only key or password, Test.
  A download client's Test lists its torrents and checks the downloads
  folder is visible and writable from Minstrel; an Exchange's Test
  reports each job switched on.
- Download clients carry a path mapping (Minstrel's /downloads vs the
  client's own name for it); search sources carry searches per hour.

Migration 0079 adds acquisition_services with its CHECKs. Ported from
Fabled Librarian: internal/indexer (Torznab, 429 Retry-After, magnet
redirects), internal/prowlarr, internal/exchange, internal/downloader,
and internal/acquire's one builder per kind, which Test already uses
so a passing Test vouches for the path a grab will take.

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

web/src/routes/admin/integrations/+page.svelte

@@ -28,6 +28,7 @@
   import { pushToast } from '#lib/stores/toast.svelte.js';
   import Modal from '#lib/components/Modal.svelte';
   import AcoustIDCard from '#lib/components/AcoustIDCard.svelte';
+  import AcquisitionCard from '#lib/components/AcquisitionCard.svelte';
   import NetworkSettingsCard from '#lib/components/NetworkSettingsCard.svelte';
   import PublicAddressCard from '#lib/components/PublicAddressCard.svelte';
   import NotificationEmailCard from '#lib/components/NotificationEmailCard.svelte';
@@ -420,6 +421,8 @@
     {/if}
   </header>
 
+  <AcquisitionCard />
+
   <!-- Lidarr panel -->
   <section class="space-y-4 rounded-xl border border-border bg-surface p-5">
     <div>

web/src/routes/admin/integrations/integrations.test.ts

@@ -37,7 +37,10 @@ vi.mock('#lib/api/admin.js', () => ({
   listUnsettledAcoustID: vi.fn(),
   // NotificationEmailCard loads on mount; left pending like AcoustIDCard.
   getNotificationEmailSettings: vi.fn(() => new Promise(() => {})),
-  updateNotificationEmailSettings: vi.fn()
+  updateNotificationEmailSettings: vi.fn(),
+  // AcquisitionCard loads on mount; left pending like AcoustIDCard.
+  listAcquisitionServices: vi.fn(() => new Promise(() => {})),
+  addAcquisitionService: vi.fn()
 }));
 
 import IntegrationsPage from './+page.svelte';