feat: remove expand toggle from collapsed sidebar, bump v0.1.54

Collapsed sidebar no longer shows an expand button — clicking any
section icon expands the sidebar and opens that section instead.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/design-system/layout/Sidebar/Sidebar.module.css

@@ -53,11 +53,6 @@
   justify-content: center;
 }
 
-.sidebarCollapsed .collapseToggle {
-  top: 52px;
-  right: 50%;
-  transform: translateX(50%);
-}
 
 .logoImg {
   width: 28px;