ProQuest Ebook Central: read chapter text via Text Only Mode live region

With chrome-devtools MCP, the ProQuest Ebook Central reader shows pages as images with no text layer, and PDF chapter downloads can fail silently in a CDP-driven browser (no file is written). Instead, once the user is signed in, turn on Text Only Mode: the 'Enable Text Only Mode' button sits in a visually hidden screen-reader panel, so a normal click times out; trigger it with an element.click() from evaluate_script. The page text then renders inside an aria-live='polite' region, not <main>, and innerText returns empty because it is visually hidden, so read textContent. Loop: read that region's textContent, click its 'Go To Next Page' link, and poll until the text changes. 26 pages took a few seconds. Without signing in, the button only shows a 'please sign in' message.