Restructure into a three-tab app with Progress, goals, and Meditation

The UX redesign's first landing (spec in UX-REDESIGN.md): ContentView
becomes a Today / Progress / Settings TabView, "Routine" replaces
"Split" in every user-facing string and view name (code-level types
keep their names), and workout starting moves to shared
WorkoutStarter / StartedWorkoutNavigator plumbing.

- New Progress tab: weekly goal streaks, workout trends, per-exercise
  weight progression, achievements, and the full history list
  (WorkoutLogsView -> WorkoutHistoryView).
- Goals: stable categories workouts roll up to, managed from Settings.
- New Meditation exercise + starter routine; timed sits record to
  Apple Health as Mind & Body sessions.

Claude-Session: https://claude.ai/code/session_012qw2itfzKyEJ1HpsFt8Ex4

CHANGELOG.md

@@ -1,12 +1,18 @@
 **July 2026**
 
+A new Progress tab shows weekly goal streaks, workout trends, per-exercise weight progression, achievements, and your full workout history.
+
+A new Meditation exercise and matching starter routine let you log timed sits, recorded in Apple Health as Mind & Body sessions.
+
 Finishing an exercise from the watch no longer risks crashing the workout screen on the iPhone.
 
 Deleting a workout no longer crashes the app.
 
 While you rest between exercises, the workout screen now previews the next exercise's figure and name so you can see what's coming up.
 
-Spoken cues can now announce the next exercise during a rest and count you into every set with "in 1, 2, 3, GO!".
+Spoken cues can now announce the next exercise during a rest and count you into every set with "in 3, 2, 1, GO!".
+
+Spoken cues now also count timed sets out, announcing the exercise's end with the same "in 3, 2, 1" countdown.
 
 A new Narration setting picks whether spoken cues give the coming-up countdown, the full setup and form read, or both.