docs: server comments say what the code does, not how it came to be (#6277)

Comment blocks in cmd/minstrel and 30 smaller internal packages, rewritten
to rule 32's standard with each citation read in context: task, milestone
and rule ids go, and so do the stories they were attached to ("used to",
"Before #N", measurements from one install, quotes, pointers to Fabled
Librarian's records and to docs/superpowers files that are not in the
repo). Where a story wrapped a real constraint, the constraint stays as a
present-tense fact.

Comments that had gone stale are corrected:
- taste.Config: the tuned values are overlaid by internal/recsettings;
  it is no longer "a later follow-up".
- StorageConfig: the data dir holds art, caches and the stream secret,
  not only playlist covers.
- the Subsonic album list and getUser comments describe what they do
  today rather than a milestone that would change it.

Checked: the non-comment token stream of every changed file matches
HEAD, and gofmt -l is empty.

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

internal/musicbrainz/client.go

@@ -20,7 +20,7 @@ const DefaultBaseURL = "https://musicbrainz.org/ws/2"
 // descriptive one.
 const UserAgent = "Minstrel/1.0 ( https://git.fabledsword.com/bvandeusen/minstrel )"
 
-// DefaultTimeout bounds one request (rule 156). A browse page with track
+// DefaultTimeout bounds one request. A browse page with track
 // lists is the slowest thing asked for.
 const DefaultTimeout = 20 * time.Second
 
@@ -33,7 +33,8 @@ const maxPages = 25
 
 var (
 	// ErrUnreachable: MusicBrainz could not be asked, or kept answering with
-	// its throttle or a server error. Callers degrade visibly (rule 164).
+	// its throttle or a server error. Callers degrade visibly: they say
+	// MusicBrainz is unreachable rather than show an empty answer.
 	ErrUnreachable = errors.New("musicbrainz: unreachable")
 	// ErrNotFound: MusicBrainz has nothing under that id.
 	ErrNotFound = errors.New("musicbrainz: not found")