docs: library comments say what the scanner and resolver do, not how they came to be (#6277)

Rewrites the internal/library comment blocks to rule 32. Task, milestone,
decision and rule ids are gone; the incidents behind them are restated as
the constraint they left (why a file is deleted before its row, why the
missing mark is a mark, why duplicates block on duration). Counts and
album names from one library are dropped from production comments; test
comments keep the names their fixtures use. The tagReadVersion log keeps
each version's before and after, without the measurements.

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

internal/library/mbids.go

@@ -14,8 +14,7 @@ type TagMBIDs struct {
 	Release string
 	Artist  string
 	// ReleaseGroup is musicbrainz_releasegroupid. Wants name albums by
-	// release group, so re-acquisition and request completion key on it
-	// (#5241).
+	// release group, so re-acquisition and request completion key on it.
 	ReleaseGroup string
 	// Recording is what tracks.mbid stores and the ListenBrainz Labs
 	// similar-recordings API keys on.
@@ -35,7 +34,7 @@ type TagMBIDs struct {
 // in Vorbis: MUSICBRAINZ_TRACKID there is the recording (the release track
 // is MUSICBRAINZ_RELEASETRACKID), so mbz files it under mbz.Track, its name
 // for the release track. Read mbz.Recording alone and every FLAC has no
-// recording id (#5637).
+// recording id.
 func ReadTagMBIDs(m tag.Metadata) TagMBIDs {
 	info := mbz.Extract(m)
 	ids := TagMBIDs{