Add window fullscreen detection and improve iPad controls spacing

Adds fullscreen detection utility to Constants.swift to determine if the window occupies the full screen on iOS. Uses this to conditionally add leading padding to player controls on iPad in non-fullscreen windows, preventing overlap with system window controls.

Shared/Constants.swift

@@ -39,6 +39,32 @@ enum Constants {
         #endif
     }
 
+    static var isWindowFullscreen: Bool {
+        #if os(iOS)
+            guard let windowScene = UIApplication.shared.connectedScenes
+                .filter({ $0.activationState == .foregroundActive })
+                .compactMap({ $0 as? UIWindowScene })
+                .first,
+                  let window = windowScene.windows.first
+            else {
+                return false
+            }
+
+            let screenBounds = windowScene.screen.bounds
+            let windowBounds = window.frame
+
+            // Check if window size matches screen bounds (accounting for small differences)
+            return abs(windowBounds.width - screenBounds.width) < 1 &&
+                   abs(windowBounds.height - screenBounds.height) < 1
+        #else
+            return false
+        #endif
+    }
+
+    static var iPadSystemControlsWidth: CGFloat {
+        50
+    }
+
     static var isTvOS: Bool {
         #if os(tvOS)
             true