Add Makefile, package.json, and initial configuration for VitePress and Slidev integration

- Introduced a Makefile for streamlined commands related to building, running, and managing presentations.
- Created package.json to define project metadata, dependencies, and scripts for development and testing.
- Added .gitignore entries to exclude build artifacts and temporary files from version control.
- Included playwright.config.mjs for end-to-end testing setup with Playwright.
- Added README.md for project documentation, outlining setup instructions and development guidelines.

tools/list-slugs.mjs

@@ -0,0 +1,20 @@
+/**
+ * Dossiers de présentation sous slides/ (hors wip_*), avec meta.json + slides.md.
+ */
+import fs from 'node:fs'
+import path from 'node:path'
+
+export function listPresentationSlugs(root) {
+  const slides = path.join(root, 'slides')
+  if (!fs.existsSync(slides)) return []
+  return fs
+    .readdirSync(slides, { withFileTypes: true })
+    .filter((d) => d.isDirectory() && !d.name.startsWith('wip_') && !d.name.startsWith('_'))
+    .map((d) => d.name)
+    .filter((slug) => {
+      return (
+        fs.existsSync(path.join(slides, slug, 'meta.json')) &&
+        fs.existsSync(path.join(slides, slug, 'slides.md'))
+      )
+    })
+}