feat(monospace): add PdfFontHeader builder for xelatex fontspec

tests/pdf-font-header.test.js

@@ -0,0 +1,55 @@
+const PdfFontHeader = require('../src/main/PdfFontHeader');
+
+describe('PdfFontHeader.build', () => {
+  test('emits fontspec with Path, family prefix, weight globs, and Ligatures=NoCommon when off', () => {
+    const tex = PdfFontHeader.build({
+      fontTtfPath: '/abs/path/JetBrainsMono-Regular.ttf',
+      boldTtfPath: '/abs/path/JetBrainsMono-Bold.ttf',
+      ligatures: false,
+    });
+    expect(tex).toContain('\\usepackage{fontspec}');
+    // \setmonofont uses the family prefix (weight suffix stripped)
+    expect(tex).toMatch(/\\setmonofont\[[^\]]*\]\{JetBrainsMono\}/);
+    // Path is the directory (no trailing filename)
+    expect(tex).toContain('Path=/abs/path/');
+    // No programming ligatures
+    expect(tex).toContain('Ligatures=NoCommon');
+    // Upright/Bold use the family-prefixed glob
+    expect(tex).toContain('UprightFont=*-Regular');
+    expect(tex).toContain('BoldFont=*-Bold');
+  });
+
+  test('emits Ligatures=TeX when on (preserves --/--- but no programming ligatures)', () => {
+    const tex = PdfFontHeader.build({
+      fontTtfPath: '/abs/JBM-Regular.ttf',
+      boldTtfPath: '/abs/JBM-Bold.ttf',
+      ligatures: true,
+    });
+    expect(tex).toContain('Ligatures=TeX');
+    expect(tex).not.toContain('Ligatures=NoCommon');
+  });
+
+  test('returns a no-op stub when font path is missing', () => {
+    const tex = PdfFontHeader.build({ fontTtfPath: null, boldTtfPath: null, ligatures: false });
+    expect(tex).toContain('% Monospace font path unavailable');
+  });
+
+  test('normalizes Windows backslashes to forward slashes', () => {
+    const tex = PdfFontHeader.build({
+      fontTtfPath: 'C:\\Users\\foo\\JetBrainsMono-Regular.ttf',
+      boldTtfPath: 'C:\\Users\\foo\\JetBrainsMono-Bold.ttf',
+      ligatures: false,
+    });
+    expect(tex).toContain('Path=C:/Users/foo/');
+    expect(tex).toMatch(/\{JetBrainsMono\}/);
+  });
+
+  test('strips the FiraCode weight suffix to derive the family prefix', () => {
+    const tex = PdfFontHeader.build({
+      fontTtfPath: '/abs/FiraCode-Regular.ttf',
+      boldTtfPath: '/abs/FiraCode-Bold.ttf',
+      ligatures: false,
+    });
+    expect(tex).toMatch(/\{FiraCode\}/);
+  });
+});