iOS: codebase cleanup — remove dead code, unify design, deduplicate patterns

- Remove swift-markdown-ui dependency (project.yml, pbxproj, Package.resolved)
- Remove all debug print() statements (APIClient, BrowseViewModel, ChapterReaderViewModel, ChapterReaderView)
- Remove dead UI stubs: isFavorited/isLiked state, heart/star buttons, empty Share/Add to Library menu items in FullPlayerView
- Remove unused audioToolbarButton toolbar builder in ChapterReaderView
- Remove unused model types: NovelListing, BookDetailData, ChapterContent
- Remove amberLight color (never referenced)
- Remove mini player interactive seek (horizontal drag/tap to seek) — progress bar is now display-only
- Fix AccentColor asset to amber #f59e0b (was orange-pink mismatch)
- Fix Discover tab icon: globe → globe.americas.fill
- Fix speed slider max: 3.0 → 2.0 in ProfileView
- Fix yearText: use static DateFormatter instead of allocating on every access
- Fix ChangePasswordView.save(): DispatchQueue.main.asyncAfter → Task.sleep
- Deduplicate navigationDestination blocks via .appNavigationDestination() View extension
- Deduplicate .alert(Error) pattern via .errorAlert() View extension

ios/LibNovel/LibNovel/Views/ChapterReader/ChapterReaderView.swift

@@ -7,6 +7,9 @@ struct ChapterReaderView: View {
     let slug: String
     let chapterNumber: Int
 
+    /// Tracks the currently displayed chapter — updated in-place by skip/auto-next
+    /// so we never accumulate stale listeners on the navigation stack.
+    @State private var currentChapter: Int
     @StateObject private var vm: ChapterReaderViewModel
     @EnvironmentObject var audioPlayer: AudioPlayerService
     @EnvironmentObject var authStore: AuthStore
@@ -14,20 +17,17 @@ struct ChapterReaderView: View {
     init(slug: String, chapterNumber: Int) {
         self.slug = slug
         self.chapterNumber = chapterNumber
+        _currentChapter = State(initialValue: chapterNumber)
         _vm = StateObject(wrappedValue: ChapterReaderViewModel(slug: slug, chapter: chapterNumber))
     }
 
     var body: some View {
-        let _ = print("[ChapterReaderView] body eval — slug=\(slug) ch=\(chapterNumber) isLoading=\(vm.isLoading) hasContent=\(vm.content != nil) error=\(vm.error ?? "nil")")
         Group {
             if vm.isLoading {
-                let _ = print("[ChapterReaderView] branch: LOADING")
                 ProgressView().frame(maxWidth: .infinity, maxHeight: .infinity)
             } else if let content = vm.content {
-                let _ = print("[ChapterReaderView] branch: CONTENT html=\(content.html.count)chars title='\(content.chapter.title)'")
                 readerContent(content)
             } else if let errMsg = vm.error {
-                let _ = print("[ChapterReaderView] branch: ERROR '\(errMsg)'")
                 VStack(spacing: 16) {
                     Image(systemName: "exclamationmark.triangle")
                         .font(.largeTitle)
@@ -42,7 +42,6 @@ struct ChapterReaderView: View {
                 }
                 .frame(maxWidth: .infinity, maxHeight: .infinity)
             } else {
-                let _ = print("[ChapterReaderView] branch: BLANK (no loading, no content, no error)")
                 Color.clear
             }
         }
@@ -54,43 +53,42 @@ struct ChapterReaderView: View {
                 floatingAudioButton
             }
         }
-        .task {
-            print("[ChapterReaderView] .task fired — calling vm.load()")
+        .task(id: currentChapter) {
             await vm.load()
-            print("[ChapterReaderView] .task completed")
         }
         .onReceive(NotificationCenter.default.publisher(for: .audioDidFinishChapter)) { note in
             guard let next = note.userInfo?["next"] as? Int else { return }
             let shouldAutoNavigate = note.userInfo?["autoNext"] as? Bool ?? false
-            if shouldAutoNavigate {
-                vm.navigateTo = next
-            }
+            // Only handle if this is the top-most (currently active) chapter view
+            guard shouldAutoNavigate, currentChapter == audioPlayer.chapter else { return }
+            navigateToChapter(next)
         }
         .onReceive(NotificationCenter.default.publisher(for: .skipToNextChapter)) { note in
             guard let next = note.userInfo?["next"] as? Int else { return }
-            vm.navigateTo = next
+            // Only the view whose chapter matches the currently playing chapter should handle this
+            guard currentChapter == audioPlayer.chapter else { return }
+            navigateToChapter(next)
         }
         .onReceive(NotificationCenter.default.publisher(for: .skipToPrevChapter)) { note in
             guard let prev = note.userInfo?["prev"] as? Int else { return }
-            vm.navigateTo = prev
-        }
-        .navigationDestination(isPresented: Binding(
-            get: { vm.navigateTo != nil },
-            set: { if !$0 { vm.navigateTo = nil } }
-        )) {
-            if let next = vm.navigateTo {
-                ChapterReaderView(slug: slug, chapterNumber: next)
-            }
+            guard currentChapter == audioPlayer.chapter else { return }
+            navigateToChapter(prev)
         }
     }
 
+    /// Navigate to a chapter in-place: reloads content without pushing to the navigation stack.
+    /// Back button always returns to BookDetailView regardless of how many chapters were visited.
+    private func navigateToChapter(_ chapter: Int) {
+        vm.switchChapter(to: chapter)
+        currentChapter = chapter
+    }
+
     // MARK: - Content
 
     @State private var webHeight: CGFloat = 800
 
     @ViewBuilder
     private func readerContent(_ content: ChapterResponse) -> some View {
-        let _ = print("[ChapterReaderView] readerContent — html=\(content.html.count)chars webHeight=\(webHeight)")
         ScrollView {
             VStack(alignment: .leading, spacing: 16) {
                 // Header
@@ -114,17 +112,21 @@ struct ChapterReaderView: View {
 
                 Divider()
 
-                // Prev / Next navigation
+                // Prev / Next navigation — in-place swap so back button always returns to book
                 HStack(spacing: 12) {
                     if let prev = content.prev {
-                        NavigationLink(value: NavDestination.chapter(slug, prev)) {
+                        Button {
+                            navigateToChapter(prev)
+                        } label: {
                             Label("Ch.\(prev)", systemImage: "chevron.left")
                                 .frame(maxWidth: .infinity)
                         }
                         .buttonStyle(.bordered)
                     }
                     if let next = content.next {
-                        NavigationLink(value: NavDestination.chapter(slug, next)) {
+                        Button {
+                            navigateToChapter(next)
+                        } label: {
                             Label("Ch.\(next)", systemImage: "chevron.right")
                                 .labelStyle(ReverseLabelStyle())
                                 .frame(maxWidth: .infinity)
@@ -171,23 +173,6 @@ struct ChapterReaderView: View {
         .padding(.trailing, 20)
         .padding(.bottom, 20)
     }
-
-    // MARK: - Audio toolbar button (kept for when player is active)
-
-    @ToolbarContentBuilder
-    private var audioToolbarButton: some ToolbarContent {
-        ToolbarItem(placement: .topBarTrailing) {
-            Button {
-                vm.toggleAudio(audioPlayer: audioPlayer, settings: authStore.settings)
-            } label: {
-                Image(systemName: audioPlayer.isActive &&
-                      audioPlayer.slug == slug &&
-                      audioPlayer.chapter == chapterNumber
-                      ? "speaker.wave.2.fill" : "speaker.wave.2")
-                    .foregroundStyle(.amber)
-            }
-        }
-    }
 }
 
 // MARK: - HTML content renderer using WKWebView
@@ -224,7 +209,6 @@ struct HTMLContentView: UIViewRepresentable {
         p { margin: 0 0 1em 0; }
         """
         let wrapped = "<html><head><style>\(css)</style><meta name='viewport' content='width=device-width, initial-scale=1'></head><body>\(html)</body></html>"
-        print("[HTMLContentView] updateUIView — html=\(html.count)chars loading into WKWebView")
         uiView.loadHTMLString(wrapped, baseURL: nil)
     }
 
@@ -233,18 +217,12 @@ struct HTMLContentView: UIViewRepresentable {
         init(_ parent: HTMLContentView) { self.parent = parent }
 
         func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!) {
-            print("[HTMLContentView] didFinish — evaluating scrollHeight")
             webView.evaluateJavaScript("document.body.scrollHeight") { result, error in
                 DispatchQueue.main.async {
-                    print("[HTMLContentView] scrollHeight result=\(String(describing: result)) error=\(String(describing: error))")
                     if let h = result as? CGFloat, h > 0 {
-                        print("[HTMLContentView] height set to CGFloat \(h)")
                         self.parent.height = h
                     } else if let h = result as? Double, h > 0 {
-                        print("[HTMLContentView] height set to Double \(h)")
                         self.parent.height = CGFloat(h)
-                    } else {
-                        print("[HTMLContentView] ⚠️ could not read height — keeping \(self.parent.height)")
                     }
                 }
             }