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/coverart/provider_mbcaa.go

@@ -11,7 +11,7 @@ import (
 	"time"
 )
 
-// FetcherConfig assembles the operator-tunable knobs for the MBCAA
+// FetcherConfig assembles the tunable knobs for the MBCAA
 // HTTP client. Kept exported because main.go's boot wiring constructs
 // one to pass into NewMBCAAProviderFromConfig.
 type FetcherConfig struct {
@@ -97,7 +97,7 @@ func (p *mbcaaProvider) FetchAlbumCover(ctx context.Context, ref AlbumRef) ([]by
 
 // FetchReleaseGroupCover retrieves the 500px front cover the Cover Art
 // Archive chose for a release group: what a search result or a wanted album
-// shows before any edition of it is held (M502 #5519).
+// shows before any edition of it is held.
 func (p *mbcaaProvider) FetchReleaseGroupCover(ctx context.Context, groupMBID string) ([]byte, error) {
 	return p.fetchFront(ctx, "release-group", groupMBID)
 }