TPdfReadingSession 类

The session never talks to a speech engine directly; the host handles OnSpeak, cancel, pause, and resume callbacks while the session tracks chunks and words

Load chunks with LoadSpoken, start with Play or PlayFrom, then call Tick as the engine reports busy or idle state

When the speech engine reports a spoken character offset, call FeedSpokenPosition so the attached TPdfView can highlight the current word

• API names, type names, file names, and PDF terms keep their original spelling so code search remains reliable
• All calls are expected on the UI thread, matching normal VCL and LCL component usage