feat: ajouter le système i18n frontend (FR/EN)

css/form.css

@@ -31,11 +31,50 @@ header {
   margin-bottom: 32px;
 }
 
+.header-top {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  gap: 16px;
+  margin-bottom: 10px;
+}
+
+.lang-switcher {
+  display: flex;
+  align-items: center;
+  gap: 4px;
+  font-size: 0.8rem;
+}
+
+.lang-sep {
+  color: #4a4a6a;
+}
+
+.lang-btn {
+  background: none;
+  border: none;
+  color: #4a4a6a;
+  cursor: pointer;
+  font-size: 0.8rem;
+  font-weight: 600;
+  padding: 2px 4px;
+  letter-spacing: 0.05em;
+  transition: color 0.2s ease;
+}
+
+.lang-btn:hover {
+  color: #e94560;
+}
+
+.lang-btn.active {
+  color: #e94560;
+}
+
 h1 {
   font-size: 2.2rem;
   font-weight: 700;
   color: #e94560;
-  margin-bottom: 10px;
+  margin-bottom: 0;
 }
 
 header p {