Add CoreData-based workout tracking app with iOS and watchOS targets

- Migrate from SwiftData to CoreData with CloudKit sync
- Add core models: Split, Exercise, Workout, WorkoutLog
- Implement tab-based UI: Workout Logs, Splits, Settings
- Add SF Symbols picker for split icons
- Add exercise picker filtered by split with exclusion of added exercises
- Integrate IndieAbout for settings/about section
- Add Yams for YAML exercise definition parsing
- Include starter exercise libraries (bodyweight, Planet Fitness)
- Add Date extensions for formatting (formattedTime, isSameDay)
- Format workout date ranges to show time-only for same-day end dates
- Add build number update script
- Add app icons

Workouts/Models/Split.swift

@@ -0,0 +1,66 @@
+import Foundation
+import CoreData
+import SwiftUI
+
+@objc(Split)
+public class Split: NSManagedObject, Identifiable {
+    @NSManaged public var name: String
+    @NSManaged public var color: String
+    @NSManaged public var systemImage: String
+    @NSManaged public var order: Int32
+
+    @NSManaged public var exercises: NSSet?
+    @NSManaged public var workouts: NSSet?
+
+    public var id: NSManagedObjectID { objectID }
+
+    static let unnamed = "Unnamed Split"
+}
+
+// MARK: - Convenience Accessors
+
+extension Split {
+    var exercisesArray: [Exercise] {
+        let set = exercises as? Set<Exercise> ?? []
+        return set.sorted { $0.order < $1.order }
+    }
+
+    var workoutsArray: [Workout] {
+        let set = workouts as? Set<Workout> ?? []
+        return set.sorted { $0.start > $1.start }
+    }
+
+    func addToExercises(_ exercise: Exercise) {
+        let items = mutableSetValue(forKey: "exercises")
+        items.add(exercise)
+    }
+
+    func removeFromExercises(_ exercise: Exercise) {
+        let items = mutableSetValue(forKey: "exercises")
+        items.remove(exercise)
+    }
+
+    func addToWorkouts(_ workout: Workout) {
+        let items = mutableSetValue(forKey: "workouts")
+        items.add(workout)
+    }
+
+    func removeFromWorkouts(_ workout: Workout) {
+        let items = mutableSetValue(forKey: "workouts")
+        items.remove(workout)
+    }
+}
+
+// MARK: - Fetch Request
+
+extension Split {
+    @nonobjc public class func fetchRequest() -> NSFetchRequest<Split> {
+        return NSFetchRequest<Split>(entityName: "Split")
+    }
+
+    static func orderedFetchRequest() -> NSFetchRequest<Split> {
+        let request = fetchRequest()
+        request.sortDescriptors = [NSSortDescriptor(keyPath: \Split.order, ascending: true)]
+        return request
+    }
+}