Harden auth and improve user management

frontend/src/layout/AppShell.tsx

@@ -23,6 +23,9 @@ function resolvePageTitle(pathname: string) {
   if (pathname.startsWith("/admin/landwirte")) {
     return "Verwaltung | Landwirte";
   }
+  if (pathname.startsWith("/admin/benutzer")) {
+    return "Verwaltung | Benutzer";
+  }
   if (pathname.startsWith("/admin/medikamente")) {
     return "Verwaltung | Medikamente";
   }
@@ -45,7 +48,7 @@ function resolvePageTitle(pathname: string) {
 }
 
 export default function AppShell() {
-  const { user, setUser } = useSession();
+  const { user, setSession } = useSession();
   const location = useLocation();
   const navigate = useNavigate();
 
@@ -76,6 +79,9 @@ export default function AppShell() {
               <div className="nav-group">
                 <div className="nav-group__label">Verwaltung</div>
                 <div className="nav-subnav">
+                  <NavLink to="/admin/benutzer" className={({ isActive }) => `nav-sublink ${isActive ? "is-active" : ""}`}>
+                    Benutzer
+                  </NavLink>
                   <NavLink to="/admin/landwirte" className={({ isActive }) => `nav-sublink ${isActive ? "is-active" : ""}`}>
                     Landwirte
                   </NavLink>
@@ -116,13 +122,13 @@ export default function AppShell() {
         <div className="sidebar__footer">
           <div className="user-chip user-chip--stacked">
             <span>{user?.displayName}</span>
-            <small>{user?.code}</small>
+            <small>{user?.email ?? user?.role}</small>
           </div>
           <button
             type="button"
             className="ghost-button"
             onClick={() => {
-              setUser(null);
+              setSession(null);
               navigate("/");
             }}
           >