Open new workouts directly and improve accessibility

Starting a workout — from the split picker or a split's exercise list —
now drops straight into its log screen once the cache catches up, via a
shared StartedWorkoutNavigator. Adds VoiceOver labels/values to the log
checkboxes and the settings button, a color-independent numbered legend
and spoken summary to the heart-rate-zone bar, and Dynamic Type scaling
to the run-flow badges and timer.

Claude-Session: https://claude.ai/code/session_01HJDQQDA9QdP8zByg43H5v3

Workouts/Views/Exercises/ExerciseListView.swift

@@ -13,7 +13,6 @@ import SwiftData
 
 struct ExerciseListView: View {
     @Environment(SyncEngine.self) private var sync
-    @Environment(\.modelContext) private var modelContext
     @Environment(\.dismiss) private var dismiss
 
     // Resolve the split by id, not a captured entity: editing a seed's exercise from
@@ -26,9 +25,9 @@ struct ExerciseListView: View {
     @State private var itemToEdit: Exercise? = nil
     @State private var itemToDelete: Exercise? = nil
     /// ID of the just-created workout; drives programmatic navigation once the
-    /// cache observer delivers the entity a beat after the file write.
+    /// cache observer delivers the entity a beat after the file write (see
+    /// `navigatesToStartedWorkout`).
     @State private var pendingWorkoutID: String? = nil
-    @State private var resolvedWorkout: Workout? = nil
 
     @Query(sort: \Workout.start, order: .reverse)
     private var workouts: [Workout]
@@ -58,15 +57,8 @@ struct ExerciseListView: View {
                     .task { dismiss() }
             }
         }
-        // Navigate to the workout log once the entity appears in the cache.
-        .navigationDestination(item: $resolvedWorkout) { workout in
-            WorkoutLogListView(workout: workout)
-        }
-        // Poll for the entity after we write the document.
-        .onChange(of: pendingWorkoutID) { _, id in
-            guard let id else { return }
-            pollForWorkout(id: id)
-        }
+        // Navigate into the workout's log screen once the entity appears in the cache.
+        .navigatesToStartedWorkout(pendingWorkoutID: $pendingWorkoutID)
     }
 
     @ViewBuilder
@@ -192,22 +184,6 @@ struct ExerciseListView: View {
         start()
     }
 
-    private func pollForWorkout(id: String) {
-        Task {
-            // Give the file→observer→cache loop a moment to complete (typically < 1 s).
-            for _ in 0..<20 {
-                try? await Task.sleep(for: .milliseconds(150))
-                if let workout = CacheMapper.fetchWorkout(id: id, in: modelContext) {
-                    resolvedWorkout = workout
-                    pendingWorkoutID = nil
-                    return
-                }
-            }
-            // If still not available after ~3 s, clear the pending ID silently.
-            pendingWorkoutID = nil
-        }
-    }
-
     private func moveExercises(from source: IndexSet, to destination: Int) {
         guard let split else { return }
         var exercises = split.exercisesArray