feat: Dynamic Island pause state, Apple-aligned spacing, and UI polish

- Add isPaused to WorkoutActivityAttributes.ContentState
- Show PAUSED badge, freeze timer to static text, dim content when paused
- Prevent stale spinner on pause by extending staleDate to 1 hour
- Add 6s timer warning color, progress bar, compact heavy timer
- Pulsing compact indicator during WORK phase
- Lock Screen margins aligned to Apple's 14pt HIG spec

tabatago-swift/TabataGo/Models/WorkoutActivityAttributes.swift

@@ -12,5 +12,6 @@ struct WorkoutActivityAttributes: ActivityAttributes {
         var trackTitle: String
         var trackArtist: String
         var isPlaying: Bool
+        var isPaused: Bool
     }
 }