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>

CLAUDE.md

@@ -2,79 +2,83 @@
 
 This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
 
-## Build & Test Commands
+## Build Commands
 
 ```bash
-# Build everything
-gradle build
+# Build the songbook PDF (two-pass for TOC)
+make
 
-# Run all tests
-gradle test
+# Remove auxiliary files
+make clean
 
-# Run tests for a specific module
-gradle :parser:test
-gradle :layout:test
-gradle :renderer-pdf:test
-gradle :app:test
-
-# Run a single test class
-gradle :parser:test --tests ChordProParserTest
-
-# Run a single test method
-gradle :parser:test --tests "ChordProParserTest.parse complete song"
-
-# Build and run CLI
-gradle :cli:run --args="build -d /path/to/project"
-gradle :cli:run --args="validate -d /path/to/project"
-
-# Launch GUI
-gradle :gui:run
+# Remove everything including PDF
+make distclean
 ```
 
-Requires Java 21 (configured in `gradle.properties`). Kotlin 2.1.10, Gradle 9.3.1.
+Requires LuaLaTeX (TeX Live) and the `leadsheets` package.
 
-## Architecture
+## Project Structure
 
-**Pipeline:** Parse → Measure → Paginate → Render
-
-`SongbookPipeline` (in `app`) orchestrates the full flow:
-1. `ConfigParser` reads `songbook.yaml` → `BookConfig`
-2. `ChordProParser` reads `.chopro` files → `Song` objects
-3. `Validator` checks config and songs
-4. `MeasurementEngine` calculates each song's height in mm using `FontMetrics`
-5. `TocGenerator` estimates TOC page count and creates entries
-6. `PaginationEngine` arranges songs into pages (greedy spread packing)
-7. `PdfBookRenderer` generates the PDF via OpenPDF
-
-**Module dependency graph:**
 ```
-model ← parser
-model ← layout
-model ← renderer-pdf
-parser, layout, renderer-pdf ← app
-app ← cli (Clikt)
-app, parser ← gui (Compose Desktop)
+songbook.tex          # Main document (title page, TOC, song inputs)
+songbook-style.sty    # Style package (geometry, fonts, leadsheets config)
+songs/                # One .tex file per song
+fonts/                # Font files (UnifrakturMaguntia for titles)
+images/               # Filler images (empty for now)
+Makefile              # Build rules (lualatex, two passes)
+output/               # Generated PDF (gitignored)
 ```
 
-`model` is the foundation with no dependencies — all data classes, the `FontMetrics` interface, and the `BookRenderer` interface live here. The `FontMetrics` abstraction decouples layout from rendering: `PdfFontMetrics` is the real implementation (in renderer-pdf), `StubFontMetrics` is used in layout tests.
+## How It Works
 
-**Pagination constraint:** Songs spanning 2 pages must start on a left (even) page. The `PaginationEngine` inserts filler images or blank pages to enforce this.
-
-## Key Types
-
-- `Song` → sections → `SongLine` → `LineSegment(chord?, text)` — chord is placed above the text segment
-- `PageContent` — sealed class: `SongPage`, `FillerImage`, `BlankPage`
-- `SectionType` — enum: `VERSE`, `CHORUS`, `BRIDGE`, `REPEAT`
-- `BuildResult` — returned by `SongbookPipeline.build()` with success/errors/counts
+Pure LaTeX songbook using the `leadsheets` package with LuaLaTeX. The style matches the Carmina Leonis songbook format:
+- Song titles in Fraktur/blackletter font (UnifrakturMaguntia)
+- Chords above lyrics in regular weight, black
+- No verse labels (verses separated by blank lines)
+- Metadata (Worte/Weise) at bottom of each song page
+- Reference book cross-references (MO, PfLB) in footer
+- Each song starts on a new page
+- A5 twoside format with page numbers at bottom-outer
 
 ## Song Format
 
-ChordPro-compatible `.chopro` files: directives in `{braces}`, chords in `[brackets]` inline with lyrics, comments with `#`. See `songs/` for examples.
+Each song uses the `leadsheets` `song` environment:
 
-## Test Patterns
+```latex
+\begin{song}{
+  title = Song Title,
+  lyrics = Lyricist,
+  composer = Composer,
+  key = G,
+  mundorgel = 42,
+  pfadfinderliederbuch = 118,
+  note = {Optional note text.},
+}
 
-Tests use `kotlin.test` annotations with Kotest assertions (`shouldBe`, `shouldHaveSize`, etc.) on JUnit 5. Layout tests use `StubFontMetrics` to avoid PDF font dependencies. App integration tests create temp directories with song files and config.
+\begin{verse}
+\chord{G}Lyrics with \chord{D}chords above. \\
+Next \chord{C}line here.
+\end{verse}
 
-## Package
+\begin{verse}
+Second verse without chords (or with).
+\end{verse}
 
-All code under `de.pfadfinder.songbook.*` — subpackages match module names (`.model`, `.parser`, `.layout`, `.renderer.pdf`, `.app`, `.cli`, `.gui`).
+\end{song}
+```
+
+**Important constraints:**
+- Use `\\` for line breaks within verses (not blank lines)
+- Never place two `\chord{}` commands without a space between them — split compound words with a hyphen: `\chord{D}Abend- \chord{A}zeit.`
+- Custom properties: `alias`, `note`, `mundorgel`, `pfadfinderliederbuch`
+- Verse types: `verse` (no label), `verse*` (for custom-labeled sections like Kanon, Ref.)
+- `musicsymbols` library skipped (requires `musix11` font not installed)
+
+## Style Details (songbook-style.sty)
+
+- Page geometry: A5, margins (top 15mm, bottom 20mm, inner 20mm, outer 12mm)
+- Body font: TeX Gyre Heros (Helvetica clone)
+- Title font: UnifrakturMaguntia (Fraktur/blackletter, from `fonts/` directory)
+- Chord format: small, regular weight, black
+- Song title template: Fraktur title only (metadata rendered at bottom via `after-song` hook)
+- Reference style based on Carmina Leonis (Pfadfinder scout songbook)