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.

slides/_shared/DeckFooter.vue

@@ -0,0 +1,74 @@
+<script setup lang="ts">
+/**
+ * Pied de page fixe pour tous les decks Slidev : retour portail + lien Specificat.
+ * Lien « Accueil » en relatif ../../../ pour fonctionner avec --base …/slides/<slug>/
+ * (ex. /slides/foo/12 → racine du site).
+ *
+ * Ne pas cibler .slidev-page en CSS global (padding, box-sizing, etc.) : Slidev centre
+ * la planche avec transform + dimensions ; modifier cette boîte casse le centrage.
+ */
+const specificat = 'https://specificat.io/'
+</script>
+
+<template>
+  <footer class="deck-footer" aria-label="Navigation du portail">
+    <a class="deck-footer__link" href="../../../">Accueil</a>
+    <span class="deck-footer__sep" aria-hidden="true">·</span>
+    <a
+      class="deck-footer__link"
+      :href="specificat"
+      rel="noopener noreferrer"
+      target="_blank"
+    >Specificat.io</a>
+    <span class="deck-footer__sep" aria-hidden="true">·</span>
+    <span class="deck-footer__rights">All rights reserved</span>
+  </footer>
+</template>
+
+<style scoped>
+.deck-footer {
+  position: fixed;
+  left: 0;
+  right: 0;
+  bottom: 0;
+  /*
+   * Slidev place la webcam sur .z-camera (= z-index 15, voir @slidev/client/uno.config.ts).
+   * Un footer plus haut (ex. 30) passait au-dessus et masquait la miniature.
+   */
+  z-index: 10;
+  display: flex;
+  flex-wrap: wrap;
+  align-items: center;
+  justify-content: center;
+  gap: 0.35em 0.5em;
+  padding: 0.35rem 2.5rem 0.55rem;
+  font-size: clamp(10px, 1.5vw, 12px);
+  line-height: 1.3;
+  color: rgba(245, 245, 245, 0.75);
+  pointer-events: none;
+  border-top: 1px solid rgba(255, 255, 255, 0.07);
+  background: linear-gradient(to top, rgba(5, 7, 9, 0.72), transparent);
+}
+
+.deck-footer__link {
+  pointer-events: auto;
+  color: #2bc9c6;
+  text-decoration: none;
+  font-weight: 500;
+}
+
+.deck-footer__link:hover,
+.deck-footer__link:focus-visible {
+  text-decoration: underline;
+  text-underline-offset: 2px;
+}
+
+.deck-footer__sep {
+  opacity: 0.65;
+}
+
+.deck-footer__rights {
+  opacity: 0.85;
+  letter-spacing: 0.02em;
+}
+</style>

slides/_shared/center-default-like-reveal.css

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+/*
+ * Reveal : center: true — le thème Slidev « default » aligne le bloc en haut-gauche.
+ * Si une planche reste en layout default (cache, ancien bundle, etc.), on centre
+ * le bloc comme le layout intégré « center ». Ne cible pas .slidev-layout.center.
+ */
+.slidev-layout.default {
+  min-height: 100%;
+  display: grid;
+  place-content: center;
+  box-sizing: border-box;
+}