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/server/hygiene_test.go

@@ -115,7 +115,7 @@ func TestSecurityHeaders(t *testing.T) {
 		t.Errorf("Permissions-Policy = %q", base.Get("Permissions-Policy"))
 	}
 
-	// Rule 94's three cases for HSTS.
+	// HSTS with no trusted proxy, and through one saying https or http.
 	if got := serve(0, "https").Get("Strict-Transport-Security"); got != "" {
 		t.Errorf("hops 0 + forwarded https: HSTS = %q, want none", got)
 	}