feat: search and grab — music release names, a quality ladder, a paced search schedule and one live grab per want (M502 #5521)

- internal/release: reads a release name (format, bitrate, bit depth and
  sample rate, source, year, video, discography) and judges it against the
  album wanted: the artist and title must be in it; video rips,
  discographies, other versions (drumless, instrumental, karaoke, remix,
  live unless the album is live…) and singles or EPs for an album are
  refused. Quality tiers on Lidarr's ladder; a .torrent's file list is read
  for format, video files and a track count short of the album.
- internal/acquire: fan-out across every search source with a narrowed
  search kept, a process-wide pacer per source, every candidate judged and
  kept with its reasons, and the grab: one live grab per want, tie-broken
  (a person's grab beats the schedule's; a better release replaces a worse
  one unless it is nearly done). Each download lands in its own folder
  under the client's downloads folder.
- internal/wanted: the search schedule, every ten minutes, never-searched
  first, then requests, missing files and followed artists, taking the
  best release when auto-grab is on (the default).
- Migration 0082: acquisition_settings (auto-grab, interval, allowed
  qualities seeded from Lidarr's "Any"), want search columns,
  want_candidates, grabs, release_blocks.
- Web: the Wanted page shows each want's last search, a Search button and
  every release found with its verdict (Grab, Grab anyway, Never this one,
  Allow again). Integrations gains "Searching and grabbing".

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

internal/api/api.go

@@ -77,6 +77,7 @@ func Mount(r chi.Router, pool *pgxpool.Pool, logger *slog.Logger, events *playev
 		acquisition:         acquire.NewStore(pool),
 		catalogue:           cat,
 		wanted:              wanted.New(pool, cat, logger),
+		searcher:            wanted.NewSearcher(pool, cat, logger),
 		catalogueSearches:   newSearchCache(),
 		catalogueArt:        catalogue.NewArt(dataDir, artSources(coverSettings)),
 		leveled:             newLeveledRenderer(dataDir, loudSettings, logger),
@@ -248,6 +249,14 @@ func Mount(r chi.Router, pool *pgxpool.Pool, logger *slog.Logger, events *playev
 				// profiles that decide which of their releases count.
 				admin.Get("/wanted", h.handleListWants)
 				admin.Delete("/wanted/{id}", h.handleRemoveWant)
+				// Searching and grabbing (M502 #5521).
+				admin.Get("/acquisition/settings", h.handleGetSearchSettings)
+				admin.Put("/acquisition/settings", h.handlePutSearchSettings)
+				admin.Get("/wanted/{id}/candidates", h.handleListCandidates)
+				admin.Post("/wanted/{id}/search", h.handleSearchWant)
+				admin.Post("/wanted/{id}/grab", h.handleGrabCandidate)
+				admin.Post("/wanted/{id}/block", h.handleBlockCandidate)
+				admin.Delete("/release-blocks/{hash}", h.handleUnblockRelease)
 				admin.Get("/follows", h.handleListFollows)
 				admin.Get("/follows/{mbid}", h.handleGetFollow)
 				admin.Put("/follows/{mbid}", h.handlePutFollow)
@@ -416,6 +425,8 @@ type handlers struct {
 	// wanted is the wanted list: follows, release-type profiles and wants
 	// (M502 #5520). Its worker runs in main; the API reads and edits.
 	wanted *wanted.Service
+	// searcher searches for wants and grabs releases for them (#5521).
+	searcher *wanted.Searcher
 	// catalogueSearches reuses recent MusicBrainz answers; nil asks every
 	// time, which is what handler tests get.
 	catalogueSearches *searchCache