Ajoute sauvegarde UI + explorateur arborescent et ajuste modales

src/main/webapp/components/header/header.jsp

@@ -1,8 +1,32 @@
-<h1>PlantUML Server</h1>
-<% if (showSocialButtons) { %>
-  <%@ include file="/components/header/social-buttons.jsp" %>
-<% } %>
-<% if (showGithubRibbon) { %>
-  <%@ include file="/components/header/github-ribbon.jsp" %>
-<% } %>
-<p>Create your <a href="https://plantuml.com">PlantUML</a> diagrams directly in your browser!</p>
+<style>
+  .header-actions {
+    display: flex;
+    gap: 0.5rem;
+    margin: 0.5rem 0;
+    flex-wrap: wrap;
+  }
+  .header-actions button {
+    background: var(--button-bg, #2c3e50);
+    color: #fff;
+    border: none;
+    border-radius: 4px;
+    padding: 0.4rem 0.75rem;
+    cursor: pointer;
+    font-weight: 600;
+  }
+  .header-actions button:hover {
+    opacity: 0.9;
+  }
+</style>
+<h1>Serveur PlantUML</h1>
+<div class="header-actions">
+  <button id="header-save-btn" type="button">Sauvegarder le diagramme</button>
+  <button id="header-load-btn" type="button">Charger un diagramme</button>
+</div>
+<% if (showSocialButtons) { %> <%@ include
+file="/components/header/social-buttons.jsp" %> <% } %> <% if (showGithubRibbon)
+{ %> <%@ include file="/components/header/github-ribbon.jsp" %> <% } %>
+<p>
+  Cr&eacute;ez vos diagrammes <a href="https://plantuml.com">PlantUML</a>
+  directement dans votre navigateur.
+</p>