Add binary exporters and template manager

- Native PDF exporter (cover, TOC, bookmarks, images, code, tables,
  text blocks); validated under Ghostscript
- Animated GIF exporter (title card, title overlay, progress bar)
- Image bundle exporter with watermark compositing
- DOCX and PPTX emitters (hand-built OOXML over our zip writer) with
  structural + relationship + XML well-formedness validation in tests
- Per-format template manager with .sfglt share archives
- Unified export dispatcher covering all nine formats
- 10 more workflow tests (52 total)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

core/templates.js

@@ -0,0 +1,99 @@
+'use strict';
+
+const fs = require('node:fs');
+const path = require('node:path');
+const { zipSync, unzipSync } = require('./zip');
+const { writeJsonSync, readJsonSync, atomicWriteFileSync, nowIso } = require('./util');
+
+/**
+ * Per-format export templates stored under settings/templates/<format>/.
+ * Templates are plain JSON option objects merged over each exporter's
+ * defaults, shareable as .sfglt zip files.
+ */
+
+const FORMATS = ['json', 'markdown', 'html-simple', 'html-rich', 'pdf', 'gif', 'image-bundle', 'docx', 'pptx'];
+
+class TemplateManager {
+  constructor(templatesDir) {
+    this.dir = templatesDir;
+  }
+
+  formatDir(format) {
+    if (!FORMATS.includes(format)) throw new Error(`unknown export format: ${format}`);
+    return path.join(this.dir, format);
+  }
+
+  fileFor(format, name) {
+    if (!/^[A-Za-z0-9 _-]+$/.test(name)) throw new Error(`bad template name: ${name}`);
+    return path.join(this.formatDir(format), `${name}.template.json`);
+  }
+
+  list(format) {
+    const dir = this.formatDir(format);
+    if (!fs.existsSync(dir)) return [];
+    return fs.readdirSync(dir)
+      .filter((f) => f.endsWith('.template.json'))
+      .map((f) => f.slice(0, -'.template.json'.length))
+      .sort();
+  }
+
+  load(format, name) {
+    const file = this.fileFor(format, name);
+    if (!fs.existsSync(file)) return null;
+    return readJsonSync(file).options || {};
+  }
+
+  save(format, name, options) {
+    writeJsonSync(this.fileFor(format, name), {
+      schemaVersion: 1, format, name, updatedAt: nowIso(), options,
+    });
+    return name;
+  }
+
+  rename(format, oldName, newName) {
+    const src = this.fileFor(format, oldName);
+    if (!fs.existsSync(src)) throw new Error(`template not found: ${oldName}`);
+    const options = readJsonSync(src).options;
+    this.save(format, newName, options);
+    fs.rmSync(src);
+  }
+
+  duplicate(format, name, copyName) {
+    const options = this.load(format, name);
+    if (options === null) throw new Error(`template not found: ${name}`);
+    return this.save(format, copyName || `${name} copy`, options);
+  }
+
+  remove(format, name) {
+    fs.rmSync(this.fileFor(format, name), { force: true });
+  }
+
+  /** Export one template as a shareable .sfglt file. */
+  exportTemplate(format, name, destFile) {
+    const options = this.load(format, name);
+    if (options === null) throw new Error(`template not found: ${name}`);
+    const manifest = { format: 'stepforge-template-archive', formatVersion: 1, exportFormat: format, name, exportedAt: nowIso() };
+    atomicWriteFileSync(destFile, zipSync([
+      { name: 'manifest.json', data: JSON.stringify(manifest, null, 2) },
+      { name: 'template.json', data: JSON.stringify({ options }, null, 2) },
+    ]));
+    return destFile;
+  }
+
+  /** Import a .sfglt file; returns { format, name }. */
+  importTemplate(file) {
+    const entries = new Map(unzipSync(fs.readFileSync(file)).map((e) => [e.name, e.data]));
+    if (!entries.has('manifest.json') || !entries.has('template.json')) {
+      throw new Error('not a StepForge template archive');
+    }
+    const manifest = JSON.parse(entries.get('manifest.json').toString('utf8'));
+    if (manifest.format !== 'stepforge-template-archive') throw new Error('unsupported template archive');
+    const { options } = JSON.parse(entries.get('template.json').toString('utf8'));
+    let name = manifest.name || 'imported';
+    if (this.list(manifest.exportFormat).includes(name)) name = `${name} (imported)`;
+    this.save(manifest.exportFormat, name, options || {});
+    return { format: manifest.exportFormat, name };
+  }
+}
+
+module.exports = { TemplateManager, FORMATS };

core/util.js

@@ -98,7 +98,8 @@ function slugify(text, fallback = 'untitled') {
   const slug = String(text || '')
     .normalize('NFKD')
     .replace(/[̀-ͯ]/g, '')
-    .replace(/[^a-zA-Z0-9._ -]+/g, '')
+    .toLowerCase()
+    .replace(/[^a-z0-9._ -]+/g, '')
     .trim()
     .replace(/\s+/g, '-')
     .slice(0, 80);