chore: remove unused .gs-sidebar-lock CSS

src/App.vue

@@ -106,13 +106,10 @@ onUnmounted(() => {
   <div id="app" class="ms-app" :data-current-login="'guest'">
     <aside class="ms-side" :class="{ collapsed: sidebarCollapsed }" :style="{ width: sidebarCollapsed ? '62px' : sidebarWidth + 'px', minWidth: sidebarCollapsed ? '62px' : sidebarWidth + 'px' }">
       <div class="gs-sidebar-toggle" @click="toggleSidebar">
-        <svg v-if="sidebarCollapsed" width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
+        <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2"
+          :style="{ transform: sidebarCollapsed ? 'rotate(0deg)' : 'rotate(180deg)' }">
           <polyline points="9 18 15 12 9 6"/>
         </svg>
-        <svg v-else class="gs-sidebar-lock" width="14" height="14" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
-          <rect x="3" y="11" width="18" height="11" rx="2" ry="2"/>
-          <path d="M7 11V7a5 5 0 0 1 10 0v4"/>
-        </svg>
       </div>
       <div class="gs-logo" :class="{ 'gs-logo-collapsed': sidebarCollapsed }">{{ sidebarCollapsed ? 'WS' : 'Workspace' }}</div>
       <nav class="gs-nav">
@@ -212,7 +209,6 @@ html, body { height: 100%; margin: 0; }
 .gs-hidden { display: none !important; }
 .gs-sidebar-toggle { display: flex; align-items: center; justify-content: flex-end; padding: 0 4px 12px 4px; cursor: pointer; color: var(--text-secondary); flex-shrink: 0; }
 .gs-sidebar-toggle svg { transition: transform 0.2s; }
-.gs-sidebar-lock { opacity: 1; }
 .ms-side.collapsed .gs-sidebar-toggle { justify-content: center; width: 100%; }
 .gs-logo-collapsed { text-align: center; padding: 8px 4px 16px 4px; font-size: 14px; }
 .ms-divider { width: 28px; flex-shrink: 0; cursor: col-resize; display: flex; align-items: center; justify-content: center; }