feat: the library's albums go on the wanted list as held, once; after that the list is the truth (M502 #5567)

A one-time job in the wanted worker lists every album in the library as a
held want, one per release group, with a record that it happened
(acquisition_settings.library_listed_at). Albums whose tags name only a
release are named on MusicBrainz first, 120 a pass; what nothing names is
counted and shown on the Held tab.

Re-acquisition now wants back only albums on the list. Taking a held album
off the list leaves its files, and it is never fetched back; albums put in
the library folder by hand afterwards are not added.

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

internal/wanted/wanted.go

@@ -2,7 +2,9 @@
 // artists, each on a release-type profile, and wanted release groups. A want
 // comes from an approved request, a followed artist's new release, or an
 // album whose files went missing; it is held once the library has a full
-// copy. Searching for open wants is #5521's.
+// copy. The library's own albums were put on the list as held once (#5567),
+// so the list is the record of what the library keeps. Searching for open
+// wants is #5521's.
 package wanted
 
 import (
@@ -172,9 +174,9 @@ func (s *Service) Run(ctx context.Context) {
 		switch {
 		case err != nil && ctx.Err() == nil:
 			s.logger.Warn("wanted: pass stopped", "err", err, "follows", res.Follows, "wanted", res.Wanted, "held", res.Held)
-		case res.Wanted > 0 || res.Held > 0 || res.Baselined > 0:
+		case res.Wanted > 0 || res.Held > 0 || res.Baselined > 0 || res.Listed > 0:
 			s.logger.Info("wanted: pass complete", "follows", res.Follows, "baselined", res.Baselined,
-				"wanted", res.Wanted, "held", res.Held)
+				"wanted", res.Wanted, "held", res.Held, "listed", res.Listed)
 		}
 		select {
 		case <-ctx.Done():
@@ -190,6 +192,7 @@ type PassResult struct {
 	Baselined int // of those, first reads
 	Wanted    int // wants recorded from follows
 	Held      int // wants the library now answers
+	Listed    int // library albums put on the list as held (#5567)
 }
 
 // Pass applies the follows due and settles open wants. An unreachable
@@ -201,6 +204,11 @@ func (s *Service) Pass(ctx context.Context) (PassResult, error) {
 	if ctx.Err() != nil {
 		return res, ctx.Err()
 	}
+	// The one-time listing of the library (#5567); a failure waits for the
+	// next pass and does not hold back settling.
+	if err := s.listLibrary(ctx, &res); err != nil && ctx.Err() == nil {
+		s.logger.Warn("wanted: list the library", "err", err)
+	}
 	if err := s.settleWants(ctx, &res); err != nil {
 		return res, err
 	}