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/config/config.go

@@ -24,12 +24,10 @@ type Config struct {
 	Recommendation RecommendationConfig `yaml:"recommendation"`
 	Branding       BrandingConfig       `yaml:"branding"`
 	// StreamSecret is the base64-decoded HMAC key used to sign UPnP /
-	// Sonos stream URLs (see internal/api/stream_token.go and
-	// docs/superpowers/specs/2026-06-03-android-output-picker-upnp-design.md).
-	// Sourced from MINSTREL_STREAM_SECRET (base64-encoded), with a
-	// per-machine fallback persisted at <Storage.DataDir>/stream_secret.
-	// Not serialized to YAML — operator-machine-scoped runtime state, not
-	// a user-facing setting. Never log the contents.
+	// Sonos stream URLs (see internal/api/stream_token.go). Sourced from
+	// MINSTREL_STREAM_SECRET (base64-encoded), with a per-machine fallback
+	// persisted at <Storage.DataDir>/stream_secret. Not read from YAML: it
+	// is per-machine state, not a setting. Never log the contents.
 	StreamSecret []byte `yaml:"-"`
 }
 
@@ -37,12 +35,8 @@ type ServerConfig struct {
 	Address string `yaml:"address"`
 }
 
-// StorageConfig points at on-disk locations the server uses for cached
-// runtime artifacts. Currently:
-//   - DataDir hosts <DataDir>/playlist_covers/{playlist_id}.jpg (M7 #352).
-//
-// More entries may grow here (e.g., transcode cache) without breaking
-// existing layouts.
+// StorageConfig points at the on-disk root for generated files: playlist
+// cover collages, artwork, caches and the stream secret.
 type StorageConfig struct {
 	// DataDir is the root for cached artifacts. Default: "./data" (relative
 	// to the working directory). Operators in production should set an
@@ -88,10 +82,9 @@ type EventsConfig struct {
 	SkipMaxDurationPlayedMs int     `yaml:"skip_max_duration_played_ms"`
 }
 
-// RecommendationConfig holds the radio path's operational knobs. The
-// scoring WEIGHTS moved to DB-backed admin settings (#1250,
-// internal/recsettings) — YAML is bootstrap-only; anything an operator
-// tunes lives in the UI with live effect.
+// RecommendationConfig holds the radio path's operational knobs. The scoring
+// weights are DB-backed admin settings (internal/recsettings), tuned in the
+// UI with live effect.
 type RecommendationConfig struct {
 	RecentlyPlayedHours int `yaml:"recently_played_hours"`
 	RadioSize           int `yaml:"radio_size"`
@@ -120,8 +113,7 @@ func Default() Config {
 		},
 		Library: LibraryConfig{
 			// On by default so a fresh install populates its library on
-			// first boot without the operator hunting for a "scan now"
-			// button. Scans are incremental (unchanged files skipped by
+			// first boot with no manual step. Scans are incremental (unchanged files skipped by
 			// mtime), so every later restart is just a cheap directory walk.
 			ScanOnStartup:     true,
 			CoverArtFromMBCAA: true,
@@ -159,15 +151,13 @@ const streamSecretBytes = 64
 const streamSecretFile = "stream_secret"
 
 // resolveStreamSecret populates cfg.StreamSecret using, in order:
-//  1. MINSTREL_STREAM_SECRET env var (operator-supplied, base64-url
-//     encoded — accepts either padded or raw form).
+//  1. MINSTREL_STREAM_SECRET env var (base64-url encoded — accepts either padded or raw form).
 //  2. <Storage.DataDir>/stream_secret if present (auto-generated on a
 //     previous boot; survives restarts so signed URLs stay valid).
 //  3. Auto-generate streamSecretBytes random bytes, persist them to that
 //     file at 0600, then use them.
 //
-// Logs (only) when an auto-generation happens so the operator can spot
-// it during first-boot. Never logs the contents.
+// Logs (only) when an auto-generation happens, so it shows on first boot. Never logs the contents.
 //
 // The loader runs before slog is initialized in cmd/minstrel/main.go;
 // log.Printf is the project's pre-logger convention.