fix: uncollapse dans hamburger topbar + padding réduit → plus haut

- Bouton show sidebar (uncollapse) supprimé de position:fixed → intégré au
  hamburger du topbar. Si sidebar collapsed → hamburger l'ouvre directement.
  Plus aucun chevauchement avec le contenu.
- .ws-split padding: 40px 24px 0 → 8px 16px 0 (gain 32px verticaux)
- Tous les éléments sont remontés, plus d'espace visible sans scroll

app/templates/base.html

@@ -335,10 +335,9 @@
     </div><!-- /sidebar-scroll -->
   </aside>
 
-  <!-- Uncollapse button (visible when sidebar hidden) -->
-  <button class="sidebar-uncollapse-btn" x-show="sidebarCollapsed" x-cloak @click="sidebarCollapsed = false" title="Show sidebar">
-    <svg width="20" height="20" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2"><line x1="3" y1="6" x2="21" y2="6"/><line x1="3" y1="12" x2="21" y2="12"/><line x1="3" y1="18" x2="21" y2="18"/></svg>
-  </button>
+  <!-- Uncollapse button → inside topbar, no overlap -->
+  <!-- (Moved into topbar block below) -->
+
 
   <style>
     [x-cloak] { display: none !important; }
@@ -350,8 +349,8 @@
     <!-- Topbar -->
     {% block topbar %}
     <header class="topbar">
-      <!-- Mobile hamburger -->
-      <button class="hamburger-btn" @click="mobileSidebarOpen = true; sidebarCollapsed = false;" title="Menu">
+      <!-- Hamburger / uncollapse sidebar -->
+      <button class="hamburger-btn" @click="sidebarCollapsed ? (sidebarCollapsed = false) : (mobileSidebarOpen = true; sidebarCollapsed = false)" title="Menu">
         <svg width="22" height="22" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2"><line x1="3" y1="6" x2="21" y2="6"/><line x1="3" y1="12" x2="21" y2="12"/><line x1="3" y1="18" x2="21" y2="18"/></svg>
       </button>
       <div class="topbar-left">