Add WatchConnectivity for bidirectional iOS-Watch sync

Implement real-time sync between iOS and Apple Watch apps using
WatchConnectivity framework. This replaces reliance on CloudKit
which doesn't work reliably in simulators.

- Add WatchConnectivityManager to both iOS and Watch targets
- Sync workouts, splits, exercises, and logs between devices
- Update iOS views to trigger sync on data changes
- Add onChange observer to ExerciseView for live progress updates
- Configure App Groups for shared container storage
- Add Watch app views: WorkoutLogsView, WorkoutLogListView, ExerciseProgressView

Workouts/WorkoutsApp.swift

@@ -14,11 +14,18 @@ import CoreData
 @main
 struct WorkoutsApp: App {
     let persistenceController = PersistenceController.shared
+    let connectivityManager = WatchConnectivityManager.shared
+
+    init() {
+        // Set up Watch connectivity with Core Data context
+        connectivityManager.setViewContext(persistenceController.viewContext)
+    }
 
     var body: some Scene {
         WindowGroup {
             ContentView()
                 .environment(\.managedObjectContext, persistenceController.viewContext)
+                .environmentObject(connectivityManager)
         }
     }
 }