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 Watch App/WorkoutSessionCoordinator.swift

@@ -61,7 +61,7 @@ enum SessionEndPlanner {
         !isRunning && !activeIDs(in: workouts).isEmpty
     }
 
-    /// The run whose split configures a self-started session: the most recently started
+    /// The run whose routine configures a self-started session: the most recently started
     /// active one (ties broken by id for determinism).
     static func runToStart(in workouts: [WorkoutDocument]) -> WorkoutDocument? {
         let ids = activeIDs(in: workouts)
@@ -148,17 +148,17 @@ final class WorkoutSessionCoordinator {
     }
 
     /// Self-start a session when an active run has none (see `SessionEndPlanner.shouldStart`).
-    /// The activity type comes from the run's split so the saved Health workout is categorized
-    /// the same way a phone-launched one would be; a run whose split is gone (deleted, or not
+    /// The activity type comes from the run's routine so the saved Health workout is categorized
+    /// the same way a phone-launched one would be; a run whose routine is gone (deleted, or not
     /// yet synced) falls back to traditional strength training.
     private func startIfNeeded(workouts: [WorkoutDocument]) {
         guard SessionEndPlanner.shouldStart(isRunning: sessionManager.isRunning, workouts: workouts),
               let run = SessionEndPlanner.runToStart(in: workouts) else { return }
-        let split = run.splitID.flatMap { id in
-            (try? context.fetch(FetchDescriptor<Split>())).flatMap { $0.first { $0.id == id } }
+        let routine = run.routineID.flatMap { id in
+            (try? context.fetch(FetchDescriptor<Routine>())).flatMap { $0.first { $0.id == id } }
         }
         let configuration = HKWorkoutConfiguration()
-        configuration.activityType = split?.activityTypeEnum.hkActivityType ?? .traditionalStrengthTraining
+        configuration.activityType = routine?.activityTypeEnum.hkActivityType ?? .traditionalStrengthTraining
         configuration.locationType = .indoor
         sessionManager.start(with: configuration)
     }