Fix card grid layout on narrow viewports with tree sidebar

The tree-layout used align-items: flex-start for the desktop sidebar,
but when switching to column direction at <900px this prevented children
from stretching to full width. Add align-items: stretch in the media
query and lower grid minmax values so cards use 2+ columns.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/src/wled_controller/static/css/tree-nav.css

@@ -190,11 +190,23 @@
     align-items: center;
 }
 
+/* ── Sidebar eats into card space — allow 2-col with smaller minmax ── */
+
+.tree-content .displays-grid,
+.tree-content .devices-grid {
+    grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
+}
+
+.tree-content .templates-grid {
+    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
+}
+
 /* ── Responsive: stack on narrow screens ── */
 
 @media (max-width: 900px) {
     .tree-layout {
         flex-direction: column;
+        align-items: stretch;
         gap: 0;
     }
 
@@ -252,4 +264,5 @@
         padding: 4px;
         margin-left: auto;
     }
+
 }