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.

tests/dist-layout.test.mjs

@@ -0,0 +1,31 @@
+/**
+ * Après npm run build : dist-portal + dist-<slug>/ à la racine.
+ */
+import { test, describe } from 'node:test'
+import assert from 'node:assert'
+import fs from 'node:fs'
+import path from 'node:path'
+import { fileURLToPath } from 'node:url'
+
+const __dirname = path.dirname(fileURLToPath(import.meta.url))
+const repoRoot = path.resolve(__dirname, '..')
+const portal = path.join(repoRoot, 'dist-portal')
+const hasPortal = fs.existsSync(portal)
+
+describe('Artefacts build (dist-portal + dist-<slug>)', () => {
+  test('portail + chaque deck', { skip: !hasPortal }, () => {
+    assert.ok(fs.existsSync(path.join(portal, 'index.html')))
+    assert.ok(fs.existsSync(path.join(portal, 'presentations', 'index.html')))
+
+    const data = JSON.parse(
+      fs.readFileSync(path.join(repoRoot, 'portal', '.vitepress', 'data', 'presentations.json'), 'utf8'),
+    )
+    for (const p of data) {
+      const slideRoot = path.join(repoRoot, `dist-${p.slug}`)
+      const slideIndex = path.join(slideRoot, 'index.html')
+      assert.ok(fs.existsSync(slideIndex), `deck manquant: dist-${p.slug}/index.html`)
+      const presIndex = path.join(portal, 'presentations', p.slug, 'index.html')
+      assert.ok(fs.existsSync(presIndex), `fiche manquante: dist-portal/presentations/${p.slug}/index.html`)
+    }
+  })
+})