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

Shared/Persistence/WorkoutsModelContainer.swift

@@ -6,14 +6,16 @@ import SwiftData
 /// safe; `SyncEngine` repopulates it from the container on next launch.
 enum WorkoutsModelContainer {
     /// Bump whenever the cache schema changes — wipes and rebuilds from files.
-    /// 2: added health-metric columns to `Workout` and `activityTypeRaw` to `Split`.
+    /// 2: added health-metric columns to `Workout` and `activityTypeRaw` to `Routine`.
     /// 3: added `categoryRaw` to `Exercise`.
     /// 4: removed the weight-reminder columns and `categoryRaw` from `Exercise` and
     ///    the `completed` column from `WorkoutLog`; added `machineSettings` to both.
     /// 5: `weight` went Int → Double on `Exercise` and `WorkoutLog`; added
     ///    `setEntries` and `logUpdatedAt` to `WorkoutLog`.
     /// 6: added `deletedLogIDs` to `Workout` (per-log merge deletion tombstones).
-    static let currentSchemaVersion = 6
+    /// 7: renamed `Split` entity to `Routine`.
+    /// 8: added `Schedule` cache entity.
+    static let currentSchemaVersion = 8
     private static let schemaVersionKey = "Workouts.persistenceSchemaVersion"
     private static let identityTokenKey = "Workouts.iCloudIdentityToken"
 
@@ -30,7 +32,7 @@ enum WorkoutsModelContainer {
     }
 
     static func make() -> ModelContainer {
-        let schema = Schema([Split.self, Exercise.self, Workout.self, WorkoutLog.self])
+        let schema = Schema([Routine.self, Exercise.self, Workout.self, WorkoutLog.self, Schedule.self])
         ensureStoreDirectoryExists()
         wipeIfNeeded()
         wipeIfAccountChanged()