🚀 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>

pages/project-single.php

@@ -0,0 +1,40 @@
+<?php
+/**
+ * Page projet individuel
+ */
+
+$slug = $GLOBALS['routeParams'][0] ?? null;
+$project = getProjectBySlug($slug);
+
+if (!$project) {
+    http_response_code(404);
+    include __DIR__ . '/404.php';
+    exit;
+}
+
+$pageTitle = $project['title'];
+$pageDescription = $project['context'];
+$currentPage = 'projets';
+
+include_template('header', compact('pageTitle', 'pageDescription'));
+include_template('navbar', compact('currentPage'));
+?>
+
+<main>
+    <section class="section">
+        <div class="container-content">
+            <div class="section-header">
+                <h1 class="section-title"><?= htmlspecialchars($project['title']) ?></h1>
+                <p class="section-subtitle">
+                    <?= htmlspecialchars($project['duration']) ?>
+                </p>
+            </div>
+
+            <p class="text-text-secondary text-center">
+                Page en construction - Story 3.4
+            </p>
+        </div>
+    </section>
+</main>
+
+<?php include_template('footer'); ?>