refactor(reader): 重构高亮选区绘制架构，对齐 WXRead 实现方案

- 移除 RDEPUBSelectableTextView，改用原生 UITextView
- 新增 NSAttributedString 自定义属性（com.rdreader.highlight/underline）注入高亮
- RDEPUBTextPageRenderView 统一绘制高亮背景、文字和选区
- RDEPUBTextSelectionController 精简，选区矩形传递给 RenderView 绘制
- 新增高亮选区复刻 WXRead 实现方案文档
- UI 测试适配新架构

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

ReadViewDemo/ReadViewDemoUITests/ReaderUITests/ReaderAnnotationTests.swift

@@ -21,17 +21,30 @@ final class ReaderAnnotationTests: XCTestCase {
         app.waitForReaderState(containing: "selection=1", timeout: 5)
 
         let highlightMenuItem = app.menuItems["高亮"]
-        let highlightButton = app.buttons["高亮"]
-        let highlightActionButton = app.buttons[IDs.readerSelectionHighlight]
+        let highlightButton = app.buttons[IDs.readerSelectionHighlight]
         if highlightMenuItem.waitForExistence(timeout: 3) {
             highlightMenuItem.tap()
-        } else if highlightActionButton.waitForExistence(timeout: 3) {
-            highlightActionButton.tap()
-        } else {
-            XCTAssertTrue(highlightButton.waitForExistence(timeout: 3), "选中文本后未出现高亮菜单")
+        } else if highlightButton.waitForExistence(timeout: 3) {
             highlightButton.tap()
+        } else {
+            XCTFail("选中文本后未出现高亮菜单")
         }
 
         app.waitForReaderState(containing: "highlights=1", timeout: 8)
     }
+
+    func testLongPressSelectionDoesNotShowToolbars() {
+        app.launchAndOpenSampleBook(pageNumber: 2)
+        app.waitForReader()
+
+        let content = app.textViews[IDs.readerSelectionText].firstMatch
+        XCTAssertTrue(content.waitForExistence(timeout: 5), "阅读内容区域未出现")
+
+        let start = content.coordinate(withNormalizedOffset: CGVector(dx: 0.35, dy: 0.42))
+        let end = content.coordinate(withNormalizedOffset: CGVector(dx: 0.68, dy: 0.42))
+        start.press(forDuration: 0.6, thenDragTo: end)
+
+        app.waitForReaderState(containing: "selection=1", timeout: 5)
+        app.waitForReaderState(containing: "toolbar=hidden", timeout: 5)
+    }
 }