docs(player): attribute the phone seek bar's removal correctly

The paragraph said #59 took the seek bar off the phone's transport.
It was plan 016 B2 — audio-player.ts says so in the comment above the
rule that does it, and CLAUDE.md's own #59 paragraph says #59 removed
shuffle, repeat and the queue button. Wrong provenance in the file
whose whole value is being right about which change did what.

Also stop tracking .pi/journal.md. It is a scheduled run's scratch log,
and this repo's memory is CLAUDE.md and .planning/ — a session log
arriving inside a feature PR is a new convention landing sideways.

frontend/src/components/audio-player/progress-line/progress-line.ts

@@ -9,8 +9,8 @@ import { PHONE_QUERY } from '../../../utils/breakpoints';
  * How far through the song we are, on the border between the mini
  * player and the tab bar (#58).
  *
- * The phone's bottom bar carries three controls and no seek bar — #59
- * took it out, because 4px of height is not a thumb target and the
+ * The phone's bottom bar carries three controls and no seek bar — plan
+ * 016 B2 took it out, because 4px of height is not a thumb target and the
  * full-screen `now-playing-view` is where seeking belongs. What went
  * with it is the one thing a mini player is expected to say without
  * being opened: how far through the song it is. This is that, and