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/me_timezone.go

@@ -1,11 +1,8 @@
 // PUT /api/me/timezone — accept the client's IANA timezone and store
-// it on the user row. The system-playlist scheduler (#392 Half B)
-// reads this column to fire each user's daily 03:00 build in their
-// local time.
-//
-// Scheduler.Refresh(ctx, userID) is invoked in a later commit (Task 3)
-// so a timezone change takes effect synchronously rather than waiting
-// for the hourly reconciliation pass.
+// it on the user row. The system-playlist scheduler reads this column
+// to fire each user's daily 03:00 build in their local time. The
+// handler calls Scheduler.Refresh so a change takes effect at once rather
+// than at the hourly reconciliation pass.
 
 package api