feat: unify reader chrome state management

- Add RDEPUBReaderUIState struct for centralized UI state model
- Refactor RDEPUBReaderChromeCoordinator with makeUIState() and applyUIState()
- Remove direct UI updates from RDEPUBReaderAnnotationCoordinator
- Consolidate updateBookmarkChrome() into updateReaderChrome()
- Update RDEPUBReaderContext, Runtime, and LocationCoordinator
- Add reader problem fix development checklist documentation

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

Sources/RDReaderView/EPUBUI/ReaderController/RDEPUBReaderChromeCoordinator.swift

@@ -57,6 +57,29 @@ final class RDEPUBReaderChromeCoordinator {
 
     /// 同步更新顶部和底部工具栏的主题、标题、按钮可用性等状态。
     func updateReaderChrome() {
+        guard let controller else { return }
+        let uiState = makeUIState()
+        applyUIState(uiState)
+        updateSearchBar()
+    }
+
+    /// 构建当前 UI 状态快照
+    func makeUIState() -> RDEPUBReaderUIState {
+        guard let controller else { return .empty }
+        return RDEPUBReaderUIState(
+            canToggleBookmark: controller.currentBookIdentifier != nil,
+            hasBookmarkAtCurrentLocation: hasBookmarkAtCurrentLocation(),
+            canShowBookmarks: !controller.activeBookmarks.isEmpty,
+            canAddHighlight: controller.configuration.allowsHighlights && controller.currentSelection != nil,
+            canShowHighlights: controller.configuration.allowsHighlights && !controller.activeHighlights.isEmpty,
+            showsTableOfContents: controller.configuration.showsTableOfContents,
+            allowsHighlights: controller.configuration.allowsHighlights,
+            showsSettingsPanel: controller.configuration.showsSettingsPanel
+        )
+    }
+
+    /// 将 UI 状态应用到顶部和底部工具栏
+    func applyUIState(_ state: RDEPUBReaderUIState) {
         guard let controller else { return }
         controller.topToolView.apply(theme: controller.configuration.theme)
         controller.topToolView.setTitle(
@@ -64,22 +87,23 @@ final class RDEPUBReaderChromeCoordinator {
                 ?? controller.parser?.metadata.title
                 ?? controller.epubURL.deletingPathExtension().lastPathComponent
         )
-        controller.topToolView.setBookmarkEnabled(controller.currentBookIdentifier != nil)
+        controller.topToolView.setBookmarkEnabled(state.canToggleBookmark)
+        controller.topToolView.setBookmarkSelected(state.hasBookmarkAtCurrentLocation)
         controller.bottomToolView.apply(theme: controller.configuration.theme)
         controller.bottomToolView.updateVisibility(
-            showsTableOfContents: controller.configuration.showsTableOfContents,
-            allowsHighlights: controller.configuration.allowsHighlights,
-            showsSettingsPanel: controller.configuration.showsSettingsPanel
+            showsTableOfContents: state.showsTableOfContents,
+            allowsHighlights: state.allowsHighlights,
+            showsSettingsPanel: state.showsSettingsPanel
         )
-        controller.bottomToolView.setBookmarksEnabled(!controller.activeBookmarks.isEmpty)
-        controller.bottomToolView.setAddHighlightEnabled(
-            controller.configuration.allowsHighlights && controller.currentSelection != nil
-        )
-        controller.bottomToolView.setHighlightsEnabled(
-            controller.configuration.allowsHighlights && !controller.activeHighlights.isEmpty
-        )
-        controller.updateBookmarkChrome()
-        updateSearchBar()
+        controller.bottomToolView.setBookmarksEnabled(state.canShowBookmarks)
+        controller.bottomToolView.setAddHighlightEnabled(state.canAddHighlight)
+        controller.bottomToolView.setHighlightsEnabled(state.canShowHighlights)
+    }
+
+    /// 判断当前位置是否有书签
+    private func hasBookmarkAtCurrentLocation() -> Bool {
+        guard let controller else { return false }
+        return context.runtime?.annotationCoordinator.currentBookmark() != nil
     }
 
     /// 弹出阅读设置面板（字号、字体、行距、分栏、主题、亮度等）。