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/scanner_test.go

@@ -148,8 +148,8 @@ func TestScanner_Integration(t *testing.T) {
 		t.Fatalf("GetTrackByPath after ScanFiles: %v", err)
 	}
 
-	// Re-running ScanFiles on the now-unchanged file (duration probed) skips it,
-	// so no album is reported as changed.
+	// Re-running ScanFiles on the now-unchanged file (duration probed) skips
+	// it, so no album is reported as changed.
 	if _, err := pool.Exec(ctx, "UPDATE tracks SET duration_ms = 1000 WHERE duration_ms = 0"); err != nil {
 		t.Fatalf("seed durations (2): %v", err)
 	}
@@ -206,14 +206,14 @@ func writeTestMP3(t *testing.T, path string, frames map[string]string) {
 	}
 }
 
-// TestScanner_AdoptsMovedFile_Integration is the #2528 proof: a renamed file
+// TestScanner_AdoptsMovedFile_Integration: a renamed file
 // must keep its existing tracks row — same id, so likes, play history and
 // playlist memberships travel with it — rather than forking into a marked ghost
 // plus a fresh zero-history row.
 //
-// Uses the MBID path. The synthetic MP3s here carry no real audio, so their audio
-// stream hash cannot be relied on — which is why the recording MBID is the signal
-// under test. The audio-hash path is covered by moved_test.go.
+// Uses the MBID path. The synthetic MP3s here carry no real audio, so their
+// audio stream hash cannot be relied on — which is why the recording MBID is
+// the signal under test. The audio-hash path is covered by moved_test.go.
 //
 // Eight tracks with one rename keeps the marked fraction at 12.5%, under
 // missingMarkMaxFraction. That is load-bearing: if the rename exceeded the cap,
@@ -309,7 +309,7 @@ func TestScanner_AdoptsMovedFile_Integration(t *testing.T) {
 	}
 }
 
-// TestScanner_ReleaseGroupMBID_Integration is #5241's scan half: a new album
+// TestScanner_ReleaseGroupMBID_Integration: a new album
 // takes its release-group id from the tag, and an album indexed before this
 // read existed gets it on the next scan, through the tagReadVersion bump,
 // without its file changing.
@@ -387,7 +387,7 @@ func TestScanner_ReleaseGroupMBID_Integration(t *testing.T) {
 }
 
 // Two albums of one name by one artist, in different release groups, are two
-// albums: Weezer's six self-titled albums shared one row until 2026-10-20. A
+// albums, as Weezer's self-titled albums are. A
 // track of the same group joins its album, and a track filed under the other
 // album's row by the old lookup moves to its own on the tagReadVersion re-read.
 func TestScanner_SameTitledAlbumsOfTwoGroupsAreTwoAlbums_Integration(t *testing.T) {