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/missing_pairs_test.go

@@ -73,7 +73,8 @@ func (f pairFixture) album(title, releaseGroup string) dbq.Album {
 	return a
 }
 
-// track adds a row; mbid "" leaves it without one, and missing marks it missing.
+// track adds a row; mbid "" leaves it without one, and missing marks it
+// missing.
 func (f pairFixture) track(album dbq.Album, title, path, mbid string, missing bool) dbq.Track {
 	f.t.Helper()
 	tr, err := f.q.UpsertTrack(context.Background(), dbq.UpsertTrackParams{
@@ -110,7 +111,7 @@ func (f pairFixture) count(sql string, args ...any) int {
 	return n
 }
 
-// The M485 proof on rows: each rule folds the pair it should, history moves onto
+// On rows: each rule folds the pair it should, history moves onto
 // the replacement, and every shape the pass must leave alone is left alone.
 func TestPairMissingTracks_Integration(t *testing.T) {
 	pool := newPool(t)
@@ -126,13 +127,13 @@ func TestPairMissingTracks_Integration(t *testing.T) {
 	edition := f.album("Pair Album (Deluxe)", "rg-pair") // same release group as albumA
 	other := f.album("Other Album", "rg-other")
 
-	// Rule title: the mp3 went, the flac came, no MBID on either, and the title's
-	// case differs as it does between old and new tags.
+	// Rule title: the mp3 went, the flac came, no MBID on either, and the
+	// title's case differs as it does between old and new tags.
 	oldMp3 := f.track(albumA, "Song One", "/m/a/01 - Song One.mp3", "", true)
 	newFlac := f.track(albumA, "song one", "/m/a/01 - song one.flac", "", false)
 
-	// Rule mbid: the same recording, retitled and filed under another edition of
-	// the same release group.
+	// Rule mbid: the same recording, retitled and filed under another edition
+	// of the same release group.
 	oldByMbid := f.track(albumA, "Old Name", "/m/a/02 - Old Name.mp3", "rec-2", true)
 	newByMbid := f.track(edition, "New Name", "/m/d/02 - New Name.flac", "rec-2", false)
 
@@ -231,10 +232,9 @@ func TestPairMissingTracks_Integration(t *testing.T) {
 	}
 }
 
-// The case that made M485: a quality upgrade. The mp3 is removed and a
-// re-encode of it arrives at a new path with no recording MBID, so move adoption
-// has nothing to match. The scan must still end with one row, carrying the old
-// row's history.
+// The common case: a quality upgrade. The mp3 is removed and a re-encode of it
+// arrives at a new path with no recording MBID, so move adoption has nothing to
+// match. The scan must still end with one row, carrying the old row's history.
 func TestScanner_FoldsUpgradedFile_Integration(t *testing.T) {
 	pool := newPool(t)
 	ctx := context.Background()