🚀 Feature: Router PHP + Pages projets (Stories 3.2 & 3.3)

Story 3.2 - Router PHP et URLs propres:
- Router PHP léger (43 lignes) avec support {slug}
- Front controller index.php
- .htaccess pour Apache
- Pages: home, projects, project-single, skills, about, contact, 404

Story 3.3 - Page liste projets vedettes:
- Grille responsive (1→2→3 colonnes)
- Template project-card.php réutilisable
- Badges technologies (max 4 + compteur)
- Lazy loading images avec fallback SVG

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

templates/project-card.php

@@ -0,0 +1,47 @@
+<?php
+/**
+ * Carte projet réutilisable
+ * @param array $project Données du projet
+ */
+
+$title = $project['title'] ?? 'Sans titre';
+$slug = $project['slug'] ?? '#';
+$thumbnail = $project['thumbnail'] ?? 'default-project.webp';
+$technologies = $project['technologies'] ?? [];
+$maxTechs = 4;
+?>
+
+<article class="card-interactive group">
+    <a href="/projet/<?= htmlspecialchars($slug, ENT_QUOTES, 'UTF-8') ?>" class="block">
+        <!-- Thumbnail -->
+        <div class="aspect-video overflow-hidden rounded-t-lg bg-surface-alt">
+            <img
+                src="/assets/img/projects/<?= htmlspecialchars($thumbnail, ENT_QUOTES, 'UTF-8') ?>"
+                alt="Aperçu du projet <?= htmlspecialchars($title, ENT_QUOTES, 'UTF-8') ?>"
+                width="400"
+                height="225"
+                loading="lazy"
+                class="w-full h-full object-cover transition-transform duration-300 group-hover:scale-105"
+                onerror="this.src='/assets/img/projects/default-project.webp'; this.onerror=null;"
+            >
+        </div>
+
+        <!-- Contenu -->
+        <div class="card-body">
+            <h3 class="text-lg font-semibold text-text-primary mb-3 group-hover:text-primary transition-colors">
+                <?= htmlspecialchars($title, ENT_QUOTES, 'UTF-8') ?>
+            </h3>
+
+            <!-- Technologies (badges) -->
+            <div class="flex flex-wrap gap-2">
+                <?php foreach (array_slice($technologies, 0, $maxTechs) as $tech): ?>
+                    <span class="badge"><?= htmlspecialchars($tech, ENT_QUOTES, 'UTF-8') ?></span>
+                <?php endforeach; ?>
+
+                <?php if (count($technologies) > $maxTechs): ?>
+                    <span class="badge badge-muted">+<?= count($technologies) - $maxTechs ?></span>
+                <?php endif; ?>
+            </div>
+        </div>
+    </a>
+</article>