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

Workouts/ContentView.swift

@@ -11,20 +11,30 @@ struct ContentView: View {
     @Environment(LiveRunState.self) private var liveRun
 
     var body: some View {
-        WorkoutLogsView()
-            // Prop the phone up and it runs the live Apple Watch workout — two-way: drive from
-            // either device and the other follows.
-            .fullScreenCover(isPresented: Binding(
-                get: { liveRun.presentable != nil },
-                set: { presenting in if !presenting { liveRun.mute() } }
-            )) {
-                if let frame = liveRun.presentable {
-                    // Re-key on the followed log so a flow-mode auto-advance (the driver
-                    // moving to the next exercise) rebuilds the mirror for the new exercise
-                    // instead of leaving a stale one pinned to the previous log.
-                    LiveRunCoverView(frame: frame) { liveRun.mute() }
-                        .id(frame.logID)
-                }
+        TabView {
+            Tab("Today", systemImage: "sun.max.fill") {
+                TodayView()
             }
+            Tab("Progress", systemImage: "chart.line.uptrend.xyaxis") {
+                ProgressTabView()
+            }
+            Tab("Settings", systemImage: "gearshape.2") {
+                SettingsView()
+            }
+        }
+        // Prop the phone up and it runs the live Apple Watch workout — two-way: drive from
+        // either device and the other follows.
+        .fullScreenCover(isPresented: Binding(
+            get: { liveRun.presentable != nil },
+            set: { presenting in if !presenting { liveRun.mute() } }
+        )) {
+            if let frame = liveRun.presentable {
+                // Re-key on the followed log so a flow-mode auto-advance (the driver
+                // moving to the next exercise) rebuilds the mirror for the new exercise
+                // instead of leaving a stale one pinned to the previous log.
+                LiveRunCoverView(frame: frame) { liveRun.mute() }
+                    .id(frame.logID)
+            }
+        }
     }
 }