feat: Bambu NC picker, collapsed by default, sidebar toggle fix, settings layout

templates/base.html

@@ -29,7 +29,7 @@
       font-weight: 700; font-size: 1.1rem;
       border-bottom: 1px solid #2e323d;
       display: flex; align-items: center; justify-content: space-between;
-      white-space: nowrap;
+      white-space: nowrap; position: relative;
     }
     #sidebar .brand .brand-text { transition: opacity .15s; }
     #sidebar.collapsed .brand .brand-text { opacity: 0; pointer-events: none; }
@@ -38,10 +38,16 @@
     #sidebarToggle {
       background: none; border: none; color: #9ba3af; cursor: pointer;
       padding: .2rem .3rem; border-radius: 4px; flex-shrink: 0;
-      transition: color .15s, background .15s;
+      transition: color .15s, background .15s, right .2s ease;
       font-size: 1rem; line-height: 1;
+      position: relative; z-index: 1;
     }
     #sidebarToggle:hover { color: #fff; background: #2e323d; }
+    /* En mode replié, centrer le bouton dans les 52px */
+    #sidebar.collapsed #sidebarToggle {
+      position: absolute;
+      left: 50%; transform: translateX(-50%);
+    }
 
     #sidebar nav { flex: 1; padding: .5rem 0; overflow: hidden; }
     #sidebar nav a {