refactor: introduce RevealManager and Article DOM context

Decouple the reveal logic from the `Article` component by introducing
a `RevealManager` component and an `ArticleDomCtx`. This allows the
reveal logic to reactively manage DOM injections and classes without
polluting the `Article` component's props or lifecycle.

Additionally, implements a robust `cleanupInjections` mechanism to
ensure that injected buttons and styling artifacts are properly removed
during navigation, role changes, or disconnections.

src/components/index.ts

@@ -16,6 +16,7 @@ import "./md-token-viewer";
 // 导出组件
 export { Article } from "./Article";
 export type { ArticleProps } from "./Article";
+export { RevealManager } from "./RevealManager";
 export { MobileSidebar, DesktopSidebar } from "./Sidebar";
 export type { SidebarProps } from "./Sidebar";
 export { FileTreeNode, HeadingNode } from "./FileTree";