Rewrite songbook as pure LaTeX project (Carmina Leonis style)

Replace the Kotlin/Gradle multi-module pipeline with a pure LaTeX
songbook using the leadsheets package and LuaLaTeX. Style matches
the Carmina Leonis (CL6) scout songbook: Fraktur titles, chords
above lyrics, metadata at page bottom, reference book footer.

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

Makefile

@@ -0,0 +1,23 @@
+MAIN     = songbook
+ENGINE   = lualatex
+OUTDIR   = output
+FLAGS    = --output-directory=$(OUTDIR) --interaction=nonstopmode
+
+.PHONY: all clean distclean
+
+all: $(OUTDIR)/$(MAIN).pdf
+
+$(OUTDIR):
+	mkdir -p $(OUTDIR)
+
+$(OUTDIR)/$(MAIN).pdf: $(MAIN).tex songbook-style.sty songs/*.tex | $(OUTDIR)
+	TEXINPUTS=.:$(shell pwd): $(ENGINE) $(FLAGS) $(MAIN).tex
+	TEXINPUTS=.:$(shell pwd): $(ENGINE) $(FLAGS) $(MAIN).tex
+
+clean:
+	rm -f $(OUTDIR)/*.aux $(OUTDIR)/*.log $(OUTDIR)/*.out \
+	      $(OUTDIR)/*.toc $(OUTDIR)/*.fls $(OUTDIR)/*.fdb_latexmk \
+	      $(OUTDIR)/*.sxd $(OUTDIR)/*.sxc
+
+distclean: clean
+	rm -f $(OUTDIR)/$(MAIN).pdf