feat: mobile dashboard — slide-in treeview + info panel + hamburger + scrim

frontend/src/styles/auth.css

@@ -601,13 +601,87 @@
   text-align: center;
 }
 
+/* Mobile Hamburger Button — nur auf Mobile sichtbar */
+.dashboard-hamburger { display: none; }
+
 @media (max-width: 768px) {
+  .dashboard-hamburger {
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    background: none;
+    border: none;
+    color: var(--color-text);
+    cursor: pointer;
+    padding: 4px;
+    margin-right: 8px;
+  }
+
   .dashboard-3col {
     grid-template-columns: 1fr;
+    position: relative;
   }
-  .dashboard-treeview, .dashboard-info-panel {
-    display: none;
+
+  /* Treeview: slide-in von links */
+  .dashboard-treeview {
+    position: fixed;
+    top: 0;
+    left: 0;
+    bottom: 0;
+    width: min(280px, 80vw);
+    z-index: 200;
+    transform: translateX(-100%);
+    transition: transform 280ms cubic-bezier(.32,.72,0,1);
+    box-shadow: 4px 0 16px rgba(0,0,0,0.3);
   }
+  .dashboard-treeview.mobile-open {
+    transform: translateX(0);
+  }
+
+  /* Info-Panel: slide-in von rechts */
+  .dashboard-info-panel {
+    position: fixed;
+    top: 0;
+    right: 0;
+    bottom: 0;
+    width: min(320px, 85vw);
+    z-index: 200;
+    transform: translateX(100%);
+    transition: transform 280ms cubic-bezier(.32,.72,0,1);
+    box-shadow: -4px 0 16px rgba(0,0,0,0.3);
+  }
+  .dashboard-info-panel.mobile-open {
+    transform: translateX(0);
+  }
+
+  /* Scrim */
+  .dashboard-scrim {
+    position: fixed;
+    inset: 0;
+    background: rgba(0,0,0,0.5);
+    z-index: 150;
+  }
+
+  /* Mobile Panel Close/Back Buttons */
+  .mobile-panel-close, .mobile-panel-back {
+    display: flex;
+    align-items: center;
+    gap: 4px;
+    background: none;
+    border: none;
+    color: var(--color-text);
+    cursor: pointer;
+    padding: 8px 12px;
+    font-size: 16px;
+    width: 100%;
+    border-bottom: 1px solid var(--color-border);
+  }
+}
+
+/* Desktop: Mobile-Buttons verstecken */
+@media (min-width: 769px) {
+  .mobile-panel-close, .mobile-panel-back { display: none; }
+  .dashboard-scrim { display: none; }
 }
 
 .dashboard-header {