fix: drawer uses fixed positioning to overlay main content

Grid cell was clipping the drawer at 72px. Now uses position: fixed
with left: 72px so it overlays the main content area and links
are clickable.

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

frontend/src/components/layout/Sidebar.tsx

@@ -436,16 +436,18 @@ export function Sidebar() {
         </div>
       </nav>
 
-      {/* Drawer panel — full height, resizable */}
+      {/* Drawer panel — fixed position, full height, resizable, overlays main content */}
       {activeFlyoutGroup && activeFlyoutGroup.children && (
         <div
-          className="flex h-full shrink-0"
+          className="fixed top-0 bottom-0 z-50 flex"
+          style={{ left: '72px' }}
           onMouseEnter={keepFlyout}
-          style={{ width: drawerWidth }}
+          onMouseLeave={closeFlyout}
         >
           <div
-            className="flex flex-col h-full flex-1 overflow-y-auto py-4 px-2"
+            className="flex flex-col h-full overflow-y-auto py-4 px-2"
             style={{
+              width: drawerWidth,
               background: '#0f1118',
               borderRight: '1px solid #1e2130',
               boxShadow: '4px 0 12px rgba(0,0,0,0.2)',