phase 3 bug fixing

frontend/src/components/layout/Sidebar.tsx

@@ -1,6 +1,7 @@
 import { useState } from 'react'
-import { NavLink } from 'react-router-dom'
+import { NavLink, Link } from 'react-router-dom'
 import { cn } from '../../lib/utils'
+import { useAuth } from '../../contexts/AuthContext'
 
 type SidebarState = 'expanded' | 'collapsed' | 'hidden'
 
@@ -64,6 +65,7 @@ interface SidebarProps {
 
 export function Sidebar({ className }: SidebarProps) {
   const [state, setState] = useState<SidebarState>('expanded')
+  const { user, isAuthenticated } = useAuth()
 
   const isCollapsed = state === 'collapsed'
   const width = isCollapsed ? 'w-14' : 'w-80'
@@ -133,8 +135,37 @@ export function Sidebar({ className }: SidebarProps) {
         </ul>
       </nav>
 
-      {/* Bottom: settings */}
-      <div className="py-2 px-2 border-t border-white/10 shrink-0">
+      {/* Bottom: user + settings */}
+      <div className="py-2 px-2 border-t border-white/10 shrink-0 flex flex-col gap-0.5">
+        {isAuthenticated ? (
+          <NavLink
+            to="/settings"
+            className={({ isActive }) =>
+              cn(
+                'flex items-center gap-3 rounded px-2 min-h-[44px] transition-colors',
+                isActive ? 'bg-white/20 text-white' : 'text-white/70 hover:bg-white/10 hover:text-white',
+              )
+            }
+            title={isCollapsed ? user?.username : undefined}
+          >
+            <div className="w-5 h-5 rounded-full bg-[#0052CC] flex items-center justify-center text-[10px] font-bold shrink-0">
+              {user?.username?.[0]?.toUpperCase()}
+            </div>
+            {!isCollapsed && <span className="text-sm font-medium truncate">{user?.username}</span>}
+          </NavLink>
+        ) : (
+          <Link
+            to="/login"
+            className="flex items-center gap-3 rounded px-2 min-h-[44px] text-white/70 hover:bg-white/10 hover:text-white transition-colors"
+            title={isCollapsed ? 'Sign in' : undefined}
+          >
+            <svg width="20" height="20" fill="none" stroke="currentColor" strokeWidth="1.5" viewBox="0 0 24 24" aria-hidden="true">
+              <path strokeLinecap="round" strokeLinejoin="round" d="M15.75 9V5.25A2.25 2.25 0 0 0 13.5 3h-6a2.25 2.25 0 0 0-2.25 2.25v13.5A2.25 2.25 0 0 0 7.5 21h6a2.25 2.25 0 0 0 2.25-2.25V15M12 9l-3 3m0 0 3 3m-3-3h12.75" />
+            </svg>
+            {!isCollapsed && <span className="text-sm font-medium">Sign in</span>}
+          </Link>
+        )}
+
         <NavLink
           to="/settings"
           className={({ isActive }) =>