Feat: Add collapsible shell

Frontend/src/components/shell/AppShell/AppShell.module.scss

@@ -23,6 +23,14 @@
   background: var(--color-surface);
 }
 
+.bodyRailCollapsed {
+  --rail-width: 0rem;
+}
+
+.bodySidebarCollapsed {
+  --sidebar-width: 0rem;
+}
+
 .railColumn {
   min-height: 0;
   display: flex;
@@ -97,7 +105,7 @@
   position: absolute;
   bottom: var(--space-3);
   left: calc(var(--space-1) + (var(--rail-width) * 0.1));
-  width: calc(var(--sidebar-width) + (var(--rail-width) * 0.9) - var(--space-2));
+  width: max(12rem, calc(var(--sidebar-width) + (var(--rail-width) * 0.9) - var(--space-2)));
   right: auto;
   z-index: calc(var(--z-modal) + 1);
   pointer-events: none;
@@ -112,6 +120,14 @@
     --rail-width: 5rem;
     --sidebar-width: 17.25rem;
   }
+
+  .bodyRailCollapsed {
+    --rail-width: 0rem;
+  }
+
+  .bodySidebarCollapsed {
+    --sidebar-width: 0rem;
+  }
 }
 
 @include respond-down(tablet) {
@@ -119,6 +135,58 @@
     --rail-width: 4.5rem;
     --sidebar-width: 13.25rem;
   }
+
+  .bodyRailCollapsed {
+    --rail-width: 0rem;
+  }
+
+  .bodySidebarCollapsed {
+    --sidebar-width: 0rem;
+  }
+}
+
+.bodyRailCollapsed .railColumn {
+  overflow: hidden;
+}
+
+.bodySidebarCollapsed .railColumn {
+  --rail-dock-clearance: 0rem;
+}
+
+.bodySidebarCollapsed:not(.bodyRailCollapsed) .railColumn {
+  --rail-bottom-offset: var(--space-3);
+}
+
+.bodySidebarCollapsed .sidebarColumn {
+  --sidebar-dock-clearance: 0rem;
+  display: none;
+  overflow: hidden;
+  border-left-width: 0;
+  border-top-width: 0;
+}
+
+.bodySidebarCollapsed .workspaceRegion {
+  grid-template-columns: minmax(0, 1fr);
+}
+
+.bodySidebarCollapsed .workspaceMain {
+  border-left-color: transparent;
+}
+
+.bodySidebarCollapsed:not(.bodyRailCollapsed) .workspaceMain {
+  border-top-width: 1px;
+  border-top-color: var(--shell-frame-border);
+  border-left-color: var(--shell-frame-border);
+  border-top-left-radius: var(--shell-top-left-radius);
+  box-shadow: none;
+}
+
+.bodySidebarCollapsed:not(.bodyRailCollapsed) .workspaceRegion::before {
+  display: none;
+}
+
+.bodySidebarCollapsed .sidebarDock {
+  display: none;
 }
 
 @include respond-down(mobile) {