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/db/dbq/models.go

@@ -218,17 +218,20 @@ type AcquisitionService struct {
 }
 
 type AcquisitionSetting struct {
-	ID                  bool
-	AutoGrab            bool
-	SearchIntervalHours int32
-	AllowedQualities    []string
-	LastPassAt          pgtype.Timestamptz
-	LastPass            []byte
-	UpdatedAt           pgtype.Timestamptz
-	ImportRoot          string
-	SeedRatio           float32
-	SeedDays            int32
-	StallHours          int32
+	ID                      bool
+	AutoGrab                bool
+	SearchIntervalHours     int32
+	AllowedQualities        []string
+	LastPassAt              pgtype.Timestamptz
+	LastPass                []byte
+	UpdatedAt               pgtype.Timestamptz
+	ImportRoot              string
+	SeedRatio               float32
+	SeedDays                int32
+	StallHours              int32
+	LibraryListingStartedAt pgtype.Timestamptz
+	LibraryListedAt         pgtype.Timestamptz
+	LibraryUnlisted         int32
 }
 
 type Album struct {