refactor: remove LockerTable component, enhance ItemTable and LoanTable with CRUD functionality, and implement AddItemForm for item creation

admin/src/Layout/Dashboard.tsx

@@ -4,7 +4,6 @@ import { Box, Heading, Text, Flex, Button } from "@chakra-ui/react";
 import Sidebar from "./Sidebar";
 import UserTable from "../components/UserTable";
 import ItemTable from "../components/ItemTable";
-import LockerTable from "../components/LockerTable";
 import LoanTable from "../components/LoanTable";
 import { MoveLeft } from "lucide-react";
 
@@ -67,7 +66,6 @@ const Dashboard: React.FC<DashboardProps> = ({ onLogout }) => {
           {activeView === "User" && <UserTable />}
           {activeView === "Ausleihen" && <LoanTable />}
           {activeView === "Gegenstände" && <ItemTable />}
-          {activeView === "Schließfächer" && <LockerTable />}
         </Box>
       </Box>
     </Flex>

admin/src/Layout/Sidebar.tsx

@@ -59,15 +59,6 @@ const Sidebar: React.FC<SidebarProps> = ({
           >
             Gegenstände
           </Link>
-          <Link
-            px={3}
-            py={2}
-            rounded="md"
-            _hover={{ bg: "gray.700", textDecoration: "none" }}
-            onClick={viewSchliessfaecher}
-          >
-            Schließfächer
-          </Link>
         </VStack>
 
         <Box mt="auto" pt={8} fontSize="xs" color="gray.500">