Add Liquid Glass effect to player controls bar

Refactor controls bar background styling with platform-specific effects:
- Add Liquid Glass effect for iOS 26+ using new glassEffect API
- Fallback to ultraThinMaterial for iOS 15-25
- Fallback to blurred black overlay for iOS 14 and earlier
- Extract background logic into reusable applyControlsBackground modifier
- Adjust controls bar vertical offset for better alignment

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Shared/Modifiers/PlayerOverlayModifier.swift

@@ -22,7 +22,7 @@ struct PlayerOverlayModifier: ViewModifier {
     @ViewBuilder var overlay: some View {
         Group {
             ControlsBar(fullScreen: .constant(false), expansionState: $expansionState, playerBar: true)
-                .offset(x: expansionState == .mini && !controlsWhenMinimized ? 10 : 0, y: 0)
+                .offset(x: expansionState == .mini && !controlsWhenMinimized ? 10 : 0, y: -3)
                 .frame(maxWidth: maxWidth, alignment: .trailing)
                 .onAppear {
                     if playerButtonIsExpanded {

Shared/Views/ControlsBar.swift

@@ -49,18 +49,15 @@ struct ControlsBar: View {
                     .frame(maxWidth: 120)
             }
         }
-
         .buttonStyle(.plain)
         .labelStyle(.iconOnly)
         .padding(.horizontal, 10)
         .padding(.vertical, 2)
         .frame(maxHeight: barHeight)
         .padding(.trailing, expansionState == .mini && !controlsWhenMinimized ? 8 : 0)
-        .modifier(ControlBackgroundModifier(enabled: backgroundEnabled))
-        .clipShape(RoundedRectangle(cornerRadius: expansionState == .full || !playerBar ? 0 : 6))
-        .overlay(
-            RoundedRectangle(cornerRadius: expansionState == .full || !playerBar ? 0 : 6)
-                .stroke(Color("ControlsBorderColor"), lineWidth: 0.5)
+        .applyControlsBackground(
+            enabled: backgroundEnabled,
+            cornerRadius: expansionState == .full || !playerBar ? 0 : 6
         )
         #if os(iOS)
         .background(
@@ -342,3 +339,53 @@ struct ControlsBar_Previews: PreviewProvider {
             .injectFixtureEnvironmentObjects()
     }
 }
+
+// MARK: - View Extension for Conditional Modifiers
+extension View {
+    @ViewBuilder
+    func `if`<Transform: View>(_ condition: Bool, transform: (Self) -> Transform) -> some View {
+        if condition {
+            transform(self)
+        } else {
+            self
+        }
+    }
+    
+    @ViewBuilder
+    func applyControlsBackground(enabled: Bool, cornerRadius: CGFloat) -> some View {
+        if enabled {
+            if #available(iOS 26.0, macOS 26.0, tvOS 26.0, *) {
+                // Use Liquid Glass on iOS 26+
+                self.glassEffect(
+                    .regular.interactive(),
+                    in: .rect(cornerRadius: cornerRadius)
+                )
+            } else if #available(iOS 15.0, macOS 12.0, tvOS 15.0, *) {
+                // Fallback to ultraThinMaterial for iOS 15+
+                self
+                    .background(
+                        RoundedRectangle(cornerRadius: cornerRadius)
+                            .fill(.ultraThinMaterial)
+                    )
+                    .overlay(
+                        RoundedRectangle(cornerRadius: cornerRadius)
+                            .stroke(Color("ControlsBorderColor"), lineWidth: 0.5)
+                    )
+            } else {
+                // Fallback for iOS 14 and earlier
+                self
+                    .background(
+                        RoundedRectangle(cornerRadius: cornerRadius)
+                            .fill(Color.black.opacity(0.3))
+                            .blur(radius: 10)
+                    )
+                    .overlay(
+                        RoundedRectangle(cornerRadius: cornerRadius)
+                            .stroke(Color("ControlsBorderColor"), lineWidth: 0.5)
+                    )
+            }
+        } else {
+            self.background(Color.clear)
+        }
+    }
+}