fix: sidebar-item flex-shrink:0 — cards were compressing to fit, eliminating scroll

Without flex-shrink:0, flex compresses all sidebar cards proportionally
when the container is shorter than their total height. Cards visually
fit the screen with no overflow — scrollTop stays 0, touch handler
has nothing to scroll. One property restores the intended overflow.

muxplex/frontend/style.css

@@ -469,6 +469,7 @@ body {
 
 .sidebar-item {
   height: 120px;
+  flex-shrink: 0;          /* prevent flex from compressing cards to fit */
   background: var(--bg-secondary);
   cursor: pointer;
   overflow: hidden;