feat: Modernize PhoneTabView with iOS 18+ Tab API

- Add support for new SwiftUI Tab API (iOS 18+) alongside legacy tabItem
- Implement mainTabsContentNew and moreTabContentNew with modern Tab() syntax
- Maintain backward compatibility with iOS versions < 18
- Use @available annotations for version-specific implementations
- Replace deprecated .tabItem with cleaner Tab(..., value:) approach
- Keep all existing functionality including badges and navigation

readeck/UI/Menu/PhoneTabView.swift

@@ -20,6 +20,13 @@ struct PhoneTabView: View {
     var body: some View {
         NavigationStack {
             GlobalPlayerContainerView {
+                if #available(iOS 18.0, *) {
+                    TabView(selection: $selectedTabIndex) {
+                        mainTabsContentNew
+                        moreTabContentNew
+                    }
+                    .accentColor(.accentColor)
+                } else {
                     TabView(selection: $selectedTabIndex) {
                         mainTabsContent
                         moreTabContent
@@ -28,10 +35,38 @@ struct PhoneTabView: View {
                 }
             }
         }
+    }
     
+    // MARK: - Tab Content (iOS 18+)
     
+    @available(iOS 18.0, *)
+    @ViewBuilder
+    private var mainTabsContentNew: some View {
+        ForEach(Array(mainTabs.enumerated()), id: \.element) { idx, tab in
+            Tab(tab.label, systemImage: tab.systemImage, value: idx) {
+                tabView(for: tab)
+            }
+        }
+    }
     
-    // MARK: - Tab Content
+    @available(iOS 18.0, *)
+    @ViewBuilder
+    private var moreTabContentNew: some View {
+        Tab("More", systemImage: "ellipsis", value: mainTabs.count) {
+            VStack(spacing: 0) {
+                moreTabsList
+                moreTabsFooter
+            }
+            .onAppear {
+                if selectedTabIndex == mainTabs.count && selectedMoreTab != nil {
+                    selectedMoreTab = nil
+                }
+            }
+        }
+        .badge(offlineBookmarksViewModel.state.localBookmarkCount > 0 ? offlineBookmarksViewModel.state.localBookmarkCount : 0)
+    }
+    
+    // MARK: - Tab Content (Legacy)
     
     @ViewBuilder
     private var mainTabsContent: some View {