feat: import with verification, and a Wanted view of its own (M502 #5522)

A finished download is checked against MusicBrainz before anything is
filed: the files are paired with an edition's tracks by position or path,
and AcoustID, tag ids, lengths and titles say whether it is the album.
What is the album is copied into the library as
Artist/Album (Year)/Artist - Album - NN - Title, tagged with Picard's
MusicBrainz ids, and scanned; the download keeps seeding. What is not is
refused: set aside, removed from the client, and the album searched for
again. A download the check cannot settle waits for a person, who imports
it anyway or refuses it. Tracks the library already holds are skipped.

The wanted list leaves Admin for a top-level Wanted view, admin-only and
web-only, with tabs for Wanted, Activity (downloads and their imports,
the ones needing a person first), Missing files, Held, Following (with the
release-type profiles, moved off Integrations) and Blocked. The search
settings gain "File new music into" when the library has several folders.

The search pass logs why each failed search failed.

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

cmd/minstrel/main.go

@@ -22,6 +22,7 @@ import (
 	"git.fabledsword.com/bvandeusen/minstrel/internal/db"
 	"git.fabledsword.com/bvandeusen/minstrel/internal/eventbus"
 	"git.fabledsword.com/bvandeusen/minstrel/internal/gc"
+	"git.fabledsword.com/bvandeusen/minstrel/internal/importer"
 	"git.fabledsword.com/bvandeusen/minstrel/internal/library"
 	"git.fabledsword.com/bvandeusen/minstrel/internal/logging"
 	"git.fabledsword.com/bvandeusen/minstrel/internal/mailer"
@@ -148,8 +149,11 @@ func run() error {
 	if acoustIDErr != nil {
 		logger.Warn("acoustid settings: using defaults (lookup off)", "err", acoustIDErr)
 	}
+	// One AcoustID client, so the lookup worker and the import's check share
+	// its pace (AcoustID allows three requests a second per key).
+	acoustIDClient := acoustid.New(acoustid.DefaultBaseURL)
 	acoustIDLookup := library.NewAcoustIDLookupWorker(pool, logger.With("component", "acoustid_lookup"),
-		acoustIDSettings, acoustid.New(acoustid.DefaultBaseURL))
+		acoustIDSettings, acoustIDClient)
 
 	contact := cfg.Library.ContactEmail
 	if contact == "" {
@@ -328,6 +332,15 @@ func run() error {
 	// when auto-grab is on.
 	go wanted.NewSearcher(pool, cat, logger.With("component", "search")).Run(ctx)
 
+	// Import with verification (M502 #5522): every minute, finished
+	// downloads are checked against their album (AcoustID, lengths, tags)
+	// and filed into the library with MusicBrainz tags, or refused.
+	var printer importer.Printer
+	if acoustIDSettings != nil {
+		printer = &importer.AcoustIDPrinter{Settings: acoustIDSettings, Client: acoustIDClient}
+	}
+	go importer.New(pool, scanner, cat, printer, cfg.Library.ScanPaths, logger.With("component", "import")).Run(ctx)
+
 	// Duplicate resolver (M498, M502): classifies the sweep's groups and, with
 	// the operator's auto-resolve on, merges the copies that are safe to merge.
 	// Started after SetNotifier so its summaries reach admins. See