feat: add direct PDF recipe download

tests/pdf-download.test.js

@@ -0,0 +1,47 @@
+const assert = require('node:assert/strict');
+const fs = require('node:fs');
+const path = require('node:path');
+const vm = require('node:vm');
+
+const html = fs.readFileSync(path.join(__dirname, '..', 'index.html'), 'utf8');
+
+assert.match(html, /id="downloadPdf"[^>]*>PDF herunterladen<\/button>/, 'PDF-Download-Button fehlt');
+
+const start = html.indexOf('/* PDF-DOWNLOAD */');
+const end = html.indexOf('/* PDF = Druckdialog', start);
+assert.ok(start >= 0 && end > start, 'PDF-Download-Implementierung fehlt');
+
+const sandbox = { Uint8Array, TextEncoder, Blob };
+vm.createContext(sandbox);
+vm.runInContext(`${html.slice(start, end)}\nglobalThis.api={pdfFilename,buildPdfBytes};`, sandbox);
+
+const { pdfFilename, buildPdfBytes } = sandbox.api;
+assert.equal(
+  pdfFilename('Napoletana', 4, 250, '24 Stunden'),
+  'Pizzateig-Napoletana-4x250g-24-Stunden.pdf'
+);
+assert.equal(
+  pdfFilename('Frei/Test', 2, 199.6, 'Same:Day'),
+  'Pizzateig-Frei-Test-2x200g-Same-Day.pdf'
+);
+assert.equal(
+  pdfFilename('Römisch tonda', 4, 200, 'Über Nacht'),
+  'Pizzateig-Romisch-tonda-4x200g-Uber-Nacht.pdf'
+);
+
+const bytes = buildPdfBytes([
+  'PIZZATEIG — Napoletana',
+  '4 Teiglinge à 250 g · 1.000 g Teig',
+  'Wasser 620 g · Salz 28 g · 20 °C',
+]);
+assert.ok(bytes instanceof Uint8Array);
+const ascii = Buffer.from(bytes).toString('latin1');
+assert.ok(ascii.startsWith('%PDF-1.4'));
+assert.match(ascii, /\/Type \/Catalog/);
+assert.match(ascii, /\/Type \/Page\b/);
+assert.match(ascii, /\/Encoding \/WinAnsiEncoding/);
+assert.match(ascii, /xref\n0 \d+/);
+assert.match(ascii, /%%EOF\n$/);
+
+fs.writeFileSync('/tmp/teig-terminal-download-test.pdf', Buffer.from(bytes));
+console.log('pdf download tests: OK');