docs: api comments say what the endpoints do, not how they came to be (#6277)

Rewrites the internal/api comment blocks to rule 32: task, milestone and
rule ids gone, the stories behind them restated as the constraint they
left, stale references corrected (the stream secret is wired from config,
the timezone handler already refreshes the scheduler, the Android app is
the native client, the design docs cited are not in the repo). Also
rewraps comment lines over 80 columns left by the earlier batches.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/api/leveled_stream.go

@@ -21,7 +21,7 @@ import (
 	"git.fabledsword.com/bvandeusen/minstrel/internal/library"
 )
 
-// The leveled stream (M464 #5001): a track rendered with the user's loudness
+// The leveled stream: a track rendered with the user's loudness
 // gain applied, for the Sonos and UPnP speakers that fetch their own audio.
 // See internal/library/leveled.go for how it is rendered.
 
@@ -49,7 +49,7 @@ func VerifyLeveledStreamToken(secret []byte, trackID string, exp int64, g librar
 }
 
 // leveledStreamPath is the leveled stream's path. It ends in .flac because
-// Sonos reads the format from the URL's extension (task #610).
+// Sonos reads the format from the URL's extension.
 func leveledStreamPath(trackID pgtype.UUID) string {
 	return "/api/tracks/" + uuidToString(trackID) + "/leveled.flac"
 }