feat(IOS-INFO-043): trim MaterialDetailView + add toolbar to MaterialReaderView

- MaterialDetailView: remove 阅读原文件, 问这份资料, 开始学习 buttons
- MaterialReaderView: add 开始学习 toolbar button
- MaterialDetailView now serves as info page accessible from reader

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

AIStudyApp/AIStudyApp/Features/MaterialReader/MaterialDetailView.swift

@@ -182,25 +182,6 @@ struct MaterialDetailView: View {
             if let status = vm.readingStatus, status != "not_started" {
                 readingProgressCard
             }
-
-            // Read original file button
-            NavigationLink(value: Route.materialReader(
-                materialId: knowledgeBaseId,
-                filePath: filePath,
-                materialType: fileType,
-                knowledgeBaseId: knowledgeBaseId,
-                title: fileName
-            )) {
-                HStack(spacing: 8) {
-                    Image(systemName: fileType == .pdf || fileType == .word || fileType == .excel ? "eye" : "book")
-                    Text("阅读原文件")
-                }
-                .font(.system(size: 15, weight: .bold))
-                .foregroundColor(.white)
-                .frame(maxWidth: .infinity).frame(height: 48)
-                .background(ZXGradient.brand)
-                .clipShape(RoundedRectangle(cornerRadius: ZXRadius.lg))
-            }
         }
     }
 
@@ -319,30 +300,6 @@ struct MaterialDetailView: View {
                     statBox(count: vm.quizCount, label: "测验", icon: "list.bullet.clipboard", color: Color.zxAccent)
                 }
 
-                // Action buttons
-                HStack(spacing: 12) {
-                    NavigationLink(value: Route.aiChat(context: ChatEntryContext(scopeType: .material, scopeId: nil, scopeName: fileName, parentKnowledgeBaseId: knowledgeBaseId, createdFrom: "material_detail"))) {
-                        Label("问这份资料", systemImage: "bubble.left.and.bubble.right")
-                            .font(.system(size: 14, weight: .semibold)).foregroundColor(Color.zxF0)
-                            .frame(maxWidth: .infinity).frame(height: 44)
-                            .background(Color.zxFill005)
-                            .clipShape(RoundedRectangle(cornerRadius: 14))
-                            .overlay(RoundedRectangle(cornerRadius: 14).stroke(Color.zxBorder008, lineWidth: 1))
-                    }
-
-                    NavigationLink(value: Route.learningSession(
-                        taskTitle: vm.kb?.title ?? "学习资料",
-                        taskType: "study",
-                        taskColorHex: "#3D7FFB"
-                    )) {
-                        Text("开始学习")
-                            .font(.system(size: 14, weight: .bold)).foregroundColor(.white)
-                            .frame(maxWidth: .infinity).frame(height: 44)
-                            .background(ZXGradient.brandPurple)
-                            .clipShape(RoundedRectangle(cornerRadius: 14))
-                    }
-                }
-
                 if vm.aiStatus == .processing {
                     Text("知习正在整理知识点，完成后可开始学习和自测")
                         .font(.system(size: 12)).foregroundColor(Color.zxF03)

AIStudyApp/AIStudyApp/Features/MaterialReader/MaterialReaderView.swift

@@ -189,6 +189,18 @@ struct MaterialReaderView: View {
                             .font(.system(size: 16))
                             .foregroundColor(Color.zxF05)
                     }
+
+                    if let kbId = knowledgeBaseId {
+                        NavigationLink(value: Route.learningSession(
+                            taskTitle: title.isEmpty ? "学习资料" : title,
+                            taskType: "study",
+                            taskColorHex: "#3D7FFB"
+                        )) {
+                            Image(systemName: "arrow.triangle.2.circlepath")
+                                .font(.system(size: 16))
+                                .foregroundColor(Color.zxF05)
+                        }
+                    }
                 }
             }
         }