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/vorbisgenre.go

@@ -17,10 +17,9 @@ import (
 //
 // dhowden/tag stores comments in a map keyed by field name
 // (vorbis.go: m.c[strings.ToLower(k)] = v), so each repeat overwrites the last
-// and only the final value survives. On the operator's library that was 3,658
-// of 4,092 FLAC files: Kupla's Life Forms declares eight genres and was stored
-// as "Instrumental Hip Hop" alone (#2500). Nothing looked corrupt; the other
-// seven were simply never seen by browse or the taste profile.
+// and only the final value survives. An album that declares eight genres
+// would be stored under the last alone; nothing would look corrupt, and the
+// other seven would never be seen by browse or the taste profile.
 //
 // The comment block is read here directly, as the ID3v2 genre frame is in
 // id3v2genre.go. Every other field still comes from dhowden/tag.
@@ -43,7 +42,8 @@ func readFLACGenreValues(rs io.ReadSeeker) ([]string, error) {
 	if _, err := io.ReadFull(rs, magic[:]); err != nil {
 		return nil, errNoGenreFrame
 	}
-	// Some taggers prepend an ID3v2 tag to a FLAC. The FLAC stream starts after it.
+	// Some taggers prepend an ID3v2 tag to a FLAC. The FLAC stream starts after
+	// it.
 	if string(magic[:3]) == "ID3" {
 		var rest [6]byte
 		if _, err := io.ReadFull(rs, rest[:]); err != nil {
@@ -172,7 +172,8 @@ func oggCommentGenres(packet []byte) ([]string, error) {
 // vorbisCommentGenres reads a comment block (vendor string, then a count of
 // length-prefixed "KEY=value" entries, little-endian lengths throughout) and
 // returns the GENRE values in file order. Field names are case-insensitive by
-// spec. Anything after the last entry, such as Vorbis's framing bit, is ignored.
+// spec. Anything after the last entry, such as Vorbis's framing bit, is
+// ignored.
 func vorbisCommentGenres(b []byte) ([]string, error) {
 	next := func() ([]byte, bool) {
 		if len(b) < 4 {