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

WorkoutsTests/ExerciseLibraryQueryTests.swift

@@ -10,7 +10,7 @@ import Testing
 struct ExerciseLibraryQueryTests {
 
     private func makeContext() throws -> ModelContext {
-        let schema = Schema([Split.self, Exercise.self, Workout.self, WorkoutLog.self])
+        let schema = Schema([Routine.self, Exercise.self, Workout.self, WorkoutLog.self])
         // cloudKitDatabase: .none matches WorkoutsModelContainer — see SeedLibraryTests.
         let config = ModelConfiguration(schema: schema, isStoredInMemoryOnly: true, cloudKitDatabase: .none)
         let container = try ModelContainer(for: schema, configurations: [config])
@@ -19,15 +19,16 @@ struct ExerciseLibraryQueryTests {
 
     @Test func machineSettingsFetchFindsRecordedSettings() throws {
         let context = try makeContext()
-        let split = Split(id: "S1", name: "Upper Body", color: "indigo",
+        // PINNED: routine documents live under the on-disk "Splits/" directory.
+        let routine = Routine(id: "S1", name: "Upper Body", color: "indigo",
                           systemImage: "dumbbell.fill", order: 0,
                           createdAt: .now, updatedAt: .now, jsonRelativePath: "Splits/S1.json")
         let exercise = Exercise(id: "E1", name: "Chest Press", order: 0, sets: 3, reps: 10,
                                 weight: 100, loadType: LoadType.weight.rawValue,
                                 durationTotalSeconds: 0,
                                 machineSettings: [MachineSetting(name: "Seat Height", value: "4")])
-        exercise.split = split
-        context.insert(split)
+        exercise.routine = routine
+        context.insert(routine)
         context.insert(exercise)
         try context.save()
 
@@ -37,12 +38,12 @@ struct ExerciseLibraryQueryTests {
         ))
         #expect(fetched.count == 1)
         #expect(fetched.first?.machineSettings == [MachineSetting(name: "Seat Height", value: "4")])
-        #expect(fetched.first?.split?.name == "Upper Body")
+        #expect(fetched.first?.routine?.name == "Upper Body")
     }
 
     @Test func weightedLogFetchGatesChart() throws {
         let context = try makeContext()
-        let workout = Workout(id: "W1", splitID: nil, splitName: "Upper Body",
+        let workout = Workout(id: "W1", routineID: nil, routineName: "Upper Body",
                               start: .now, end: .now, statusRaw: WorkoutStatus.completed.rawValue,
                               createdAt: .now, updatedAt: .now,
                               jsonRelativePath: "Workouts/2026/07/W1.json")