Add ForewordConfig to BookConfig, Foreword model type, ForewordParser for
text files (quote/paragraphs/signatures), ForewordPage in PageContent,
pipeline integration to insert foreword after TOC, and PDF rendering with
styled quote, horizontal rule separator, word-wrapped paragraphs, and
right-aligned signatures.
Also adds Gradle wrapper and adjusts build toolchain for JDK 25 compat.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
8e4728c55a