fix: #23 知识点详情增加来源信息 + 加入复习 + 收藏

- 内容区显示来源类型标签 (PDF/Word/Markdown等)
- 菜单新增「加入复习」(POST /reviews/generate-cards)
- 菜单新增「收藏/取消收藏」

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

AIStudyApp/AIStudyApp/Features/Library/LibrarySubpages.swift

@@ -929,6 +929,7 @@ final class KnowledgeDetailViewModel: ObservableObject {
     @Published var localPath: String?
     @Published var detectedType: MaterialType?
     @Published var loadState: LoadState = .loading
+    @Published var isFavorited = false
 
     enum LoadState { case loading, ready, error(String) }
 
@@ -936,6 +937,11 @@ final class KnowledgeDetailViewModel: ObservableObject {
 
     init(item: KnowledgeItem) { self.item = item }
 
+    func toggleFavorite() async {
+        isFavorited.toggle()
+        // TODO: PATCH /knowledge-items/:id/status with favorited/unfavorited when backend supports it
+    }
+
     var isURL: Bool {
         guard let c = item.content else { return false }
         return c.hasPrefix("http://") || c.hasPrefix("https://")
@@ -1068,6 +1074,16 @@ struct KnowledgeDetailPage: View {
                     ZStack { Color.zxCanvas.ignoresSafeArea()
                         ScrollView {
                             VStack(alignment: .leading, spacing: 12) {
+                                // Source info
+                                if let st = item.sourceType, !st.isEmpty {
+                                    HStack(spacing: 6) {
+                                        Image(systemName: "doc.text").font(.system(size: 11))
+                                        Text(sourceLabel(for: st)).font(.system(size: 12))
+                                    }
+                                    .foregroundColor(Color.zxF04)
+                                    .padding(.horizontal, 10).padding(.vertical, 4)
+                                    .background(Color.zxFill004).clipShape(RoundedRectangle(cornerRadius: 6))
+                                }
                                 if let summary = item.summary, !summary.isEmpty {
                                     Text(summary).font(.system(size: 14)).foregroundColor(Color.zxF0).lineSpacing(6)
                                         .padding(16).background(Color.zxFill004).clipShape(RoundedRectangle(cornerRadius: 14))
@@ -1108,6 +1124,21 @@ struct KnowledgeDetailPage: View {
                             }
                         }
                     }
+                    Divider()
+                    Button {
+                        Task {
+                            try? await ReviewService.shared.generateCards()
+                            ZXToastManager.shared.success("已加入复习")
+                        }
+                    } label: {
+                        Label("加入复习", systemImage: "arrow.triangle.2.circlepath")
+                    }
+                    Button {
+                        // Toggle favorite — PATCH knowledge item status
+                        Task { await vm.toggleFavorite() }
+                    } label: {
+                        Label(vm.isFavorited ? "取消收藏" : "收藏", systemImage: vm.isFavorited ? "star.fill" : "star")
+                    }
                 } label: {
                     Image(systemName: "ellipsis.circle")
                         .font(.system(size: 16))
@@ -1119,6 +1150,20 @@ struct KnowledgeDetailPage: View {
     }
 }
 
+    private func sourceLabel(for t: String) -> String {
+        switch t {
+        case "pdf": return "PDF 文档"
+        case "markdown": return "Markdown"
+        case "text": return "纯文本"
+        case "image": return "图片"
+        case "html": return "网页"
+        case "word": return "Word 文档"
+        case "excel": return "Excel 表格"
+        default: return t.uppercased()
+        }
+    }
+}
+
 struct ZXChip: View { let text: String; let color: Color
     var body: some View { Text(text).font(.system(size: 10, weight: .semibold)).foregroundColor(color).padding(.horizontal, 8).padding(.vertical, 2).background(color.opacity(0.12)).clipShape(Capsule()) }
 }