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/scrobble/threshold.go

@@ -7,9 +7,8 @@ package scrobble
 // recommended scrobble threshold: ≥240 seconds played OR ≥50% of the
 // track length played.
 //
-// The two thresholds are deliberately separate from M2's skip-detection
-// thresholds (which serve a different purpose — internal engine signal
-// for the scoring formula's skip penalty).
+// The two thresholds are deliberately separate from the skip-detection
+// thresholds, which feed the scoring formula's skip penalty instead.
 func Qualifies(durationPlayedMs int, completionRatio float64) bool {
 	return durationPlayedMs >= 240_000 || completionRatio >= 0.5
 }

internal/scrobble/worker.go

@@ -14,7 +14,7 @@ import (
 )
 
 // backoffSchedule maps the failure count (1-indexed) to the delay before
-// the next attempt. Per spec §M4a: 1m → 5m → 30m → 2h → 6h, then give up.
+// the next attempt: 1m → 5m → 30m → 2h → 6h, then give up.
 var backoffSchedule = []time.Duration{
 	1 * time.Minute,
 	5 * time.Minute,