feat: add support for foreword/preface pages (Closes #1)

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>

renderer-pdf/src/main/kotlin/de/pfadfinder/songbook/renderer/pdf/PdfBookRenderer.kt

@@ -74,6 +74,14 @@ class PdfBookRenderer : BookRenderer {
                     cb.beginText()
                     cb.endText()
                 }
+                is PageContent.ForewordPage -> {
+                    val leftMargin = if (isRightPage) marginInner else marginOuter
+                    renderForewordPage(
+                        cb, fontMetrics, config,
+                        pageContent.foreword, pageContent.pageIndex,
+                        contentTop, leftMargin, contentWidth
+                    )
+                }
             }
 
             pageDecorator.addPageNumber(cb, currentPageNum, pageSize.width, pageSize.height)
@@ -235,6 +243,119 @@ class PdfBookRenderer : BookRenderer {
         }
     }
 
+    private fun renderForewordPage(
+        cb: PdfContentByte,
+        fontMetrics: PdfFontMetrics,
+        config: BookConfig,
+        foreword: Foreword,
+        pageIndex: Int,
+        contentTop: Float,
+        leftMargin: Float,
+        contentWidth: Float
+    ) {
+        var y = contentTop
+        val bodyFontSpec = config.fonts.lyrics
+        val bodyFont = fontMetrics.getBaseFont(bodyFontSpec)
+        val bodySize = bodyFontSpec.size
+        val lineHeight = bodySize * 1.5f
+
+        if (pageIndex == 0) {
+            // Page 1: Quote + separator + first paragraphs
+
+            // Render quote in italic (bold)
+            val quoteText = foreword.quote
+            if (quoteText != null) {
+                val quoteFont = fontMetrics.getBaseFontBold(bodyFontSpec)
+                val quoteSize = bodySize * 1.1f
+
+                // Word-wrap the quote text
+                val quoteLines = wrapText(quoteText, quoteFont, quoteSize, contentWidth)
+                for (quoteLine in quoteLines) {
+                    cb.beginText()
+                    cb.setFontAndSize(quoteFont, quoteSize)
+                    cb.setColorFill(Color.DARK_GRAY)
+                    cb.setTextMatrix(leftMargin, y - quoteSize)
+                    cb.showText(quoteLine)
+                    cb.endText()
+                    y -= quoteSize * 1.5f
+                }
+
+                y -= 6f  // gap before separator
+
+                // Horizontal rule
+                cb.setLineWidth(0.5f)
+                cb.setColorStroke(Color.GRAY)
+                cb.moveTo(leftMargin, y)
+                cb.lineTo(leftMargin + contentWidth, y)
+                cb.stroke()
+                y -= 10f  // gap after separator
+            }
+
+            // Render body paragraphs
+            for (paragraph in foreword.paragraphs) {
+                val wrappedLines = wrapText(paragraph, bodyFont, bodySize, contentWidth)
+                for (wrappedLine in wrappedLines) {
+                    cb.beginText()
+                    cb.setFontAndSize(bodyFont, bodySize)
+                    cb.setColorFill(Color.BLACK)
+                    cb.setTextMatrix(leftMargin, y - bodySize)
+                    cb.showText(wrappedLine)
+                    cb.endText()
+                    y -= lineHeight
+                }
+                y -= lineHeight * 0.5f  // paragraph spacing
+            }
+
+            // Render signatures (right-aligned)
+            if (foreword.signatures.isNotEmpty()) {
+                y -= lineHeight  // extra gap before signatures
+                val metaFont = fontMetrics.getBaseFont(config.fonts.metadata)
+                val metaSize = config.fonts.metadata.size
+                for (signature in foreword.signatures) {
+                    val sigWidth = metaFont.getWidthPoint(signature, metaSize)
+                    cb.beginText()
+                    cb.setFontAndSize(metaFont, metaSize)
+                    cb.setColorFill(Color.DARK_GRAY)
+                    cb.setTextMatrix(leftMargin + contentWidth - sigWidth, y - metaSize)
+                    cb.showText(signature)
+                    cb.endText()
+                    y -= metaSize * 1.8f
+                }
+            }
+        } else {
+            // Page 2: blank (or overflow content if needed in the future)
+            cb.beginText()
+            cb.endText()
+        }
+    }
+
+    /**
+     * Simple word-wrap: splits text into lines that fit within maxWidth (in points).
+     */
+    private fun wrapText(text: String, font: BaseFont, fontSize: Float, maxWidth: Float): List<String> {
+        val words = text.split(" ")
+        val lines = mutableListOf<String>()
+        var currentLine = StringBuilder()
+
+        for (word in words) {
+            val testLine = if (currentLine.isEmpty()) word else "$currentLine $word"
+            val testWidth = font.getWidthPoint(testLine, fontSize)
+            if (testWidth <= maxWidth) {
+                currentLine = StringBuilder(testLine)
+            } else {
+                if (currentLine.isNotEmpty()) {
+                    lines.add(currentLine.toString())
+                }
+                currentLine = StringBuilder(word)
+            }
+        }
+        if (currentLine.isNotEmpty()) {
+            lines.add(currentLine.toString())
+        }
+
+        return lines
+    }
+
     private fun renderFillerImage(document: Document, imagePath: String, pageSize: Rectangle) {
         try {
             val img = Image.getInstance(imagePath)