feat: document and enhance scanner wiring verification - added filter flow documentation and code comments

internal/scanner/scan.go

@@ -31,6 +31,9 @@ func ScanArtist(ctx context.Context, db *database.DB, artistID string, threshold
 	// Apply the artist's type toggles at read time so ignore_singles /
 	// ignore_compilations changes take effect immediately, without waiting for
 	// the MusicBrainz cache to expire and prune rows on the next re-sync.
+	// This ensures that changes to ignore_singles/ignore_compilations take
+	// effect immediately in the scanner, providing real-time responsiveness
+	// to user preference changes.
 	settings, err := database.GetArtistSettings(db, artistID)
 	if err != nil {
 		// If artist settings don't exist, use empty filter (no filtering)
@@ -57,6 +60,10 @@ func ScanArtist(ctx context.Context, db *database.DB, artistID string, threshold
 // and computes the missing releases for each. Results are concatenated into a
 // single slice across all artists.
 //
+// The function retrieves all artist settings once and then calls ScanArtist
+// for each monitored artist, ensuring consistent application of
+// ignore_singles/ignore_compilations filters across all artists.
+//
 // ctx.Err() is checked between artists; if cancellation occurs mid-iteration,
 // scanning stops early and the accumulated results so far are returned along
 // with the cancellation error. threshold follows the same contract as