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/RDEPUBReaderContext.swift

@@ -369,9 +369,4 @@ final class RDEPUBReaderContext {
     func applyReaderViewConfiguration() {
         controller?.applyReaderViewConfiguration()
     }
-
-    /// 同步书签按钮的 UI 状态。
-    func updateBookmarkChrome() {
-        controller?.updateBookmarkChrome()
-    }
 }