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/notifications/kinds.go

@@ -1,17 +1,16 @@
-// Package notifications is the one writer of the per-user notifications inbox
-// (M489, #726). Producers across the server call Notifier.Notify; nothing else
+// Package notifications is the one writer of the per-user notifications
+// inbox. Producers across the server call Notifier.Notify; nothing else
 // inserts into user_notifications.
 //
-// The event bus alone was fire-and-forget: a client that was not connected
-// when a request completed, or when tracks went missing, never heard of it. A
-// row here is the durable record. The bus only nudges open clients to come
-// and read it.
+// The event bus is fire-and-forget: a client that is not connected when a
+// request completes, or when tracks go missing, never hears of it. A row here
+// is the durable record. The bus only nudges open clients to come and read
+// it.
 package notifications
 
-// Kind names one sort of notification. The set is CHECK-gated in migration
-// 0073, swapped since by 0075 (rule 36): a new kind adds its value in a
-// migration of the same change, and TestEveryKindPassesTheSchemaChecks
-// fails until it does.
+// Kind names one sort of notification. The set is CHECK-gated in the schema:
+// a new kind adds its value (DROP + ADD of the CHECK) in a migration of the
+// same change, and TestEveryKindPassesTheSchemaChecks fails until it does.
 type Kind string
 
 const (
@@ -23,9 +22,8 @@ const (
 	KindScanFailed        Kind = "scan_failed"
 	KindTracksMissing     Kind = "tracks_missing"
 	KindDuplicatesFound   Kind = "duplicates_found"
-	// KindDuplicatesResolved: the duplicate resolver (M498) merged copies on
-	// its own. The operator asked for that to
-	// happen automatically; this is how it stays visible.
+	// KindDuplicatesResolved: the duplicate resolver merged copies on its
+	// own. This is how an automatic merge stays visible.
 	KindDuplicatesResolved Kind = "duplicates_resolved"
 	KindPlaybackErrors     Kind = "playback_errors"
 )