Initial implementation of songbook toolset

Kotlin/JVM multi-module project for generating a scout songbook PDF
from ChordPro-format text files. Includes ChordPro parser, layout engine
with greedy spread packing for double-page songs, OpenPDF renderer,
CLI (Clikt), Compose Desktop GUI, and 5 sample songs.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

songbook.yaml

@@ -0,0 +1,37 @@
+book:
+  title: "Pfadfinder Liederbuch"
+  subtitle: "Beispiel-Ausgabe"
+  edition: "1. Auflage, 2026"
+  format: A5
+
+songs:
+  directory: "./songs"
+  order: alphabetical
+
+fonts:
+  lyrics:    { family: "Helvetica", size: 10 }
+  chords:    { family: "Helvetica", size: 9, color: "#333333" }
+  title:     { family: "Helvetica", size: 14 }
+  metadata:  { family: "Helvetica", size: 8 }
+  toc:       { family: "Helvetica", size: 9 }
+
+layout:
+  margins: { top: 15, bottom: 15, inner: 20, outer: 12 }
+  chord_line_spacing: 3
+  verse_spacing: 4
+  page_number_position: bottom-outer
+
+images:
+  directory: "./images"
+
+reference_books:
+  - id: mundorgel
+    name: "Mundorgel"
+    abbreviation: "MO"
+  - id: pfadfinderliederbuch
+    name: "Pfadfinderliederbuch"
+    abbreviation: "PfLB"
+
+output:
+  directory: "./output"
+  filename: "liederbuch.pdf"