Restore enterprise/LDAP login mode detection

- Added /users/auth-mode public endpoint to detect LDAP status
- Updated frontend to call getAuthMode() instead of hardcoded false
- Login page now automatically switches to enterprise mode when LDAP is enabled
- Fixes missing LDAP user login UI that was previously disabled with TODO comment

This restores the functionality that was commented out earlier where the login
page would auto-detect whether to show local user list or enterprise username input.

frontend/app/globals.css

@@ -5,7 +5,7 @@
 @tailwind utilities;
 
 @layer base {
-    :root {
+        :root {
     /* Base colors from DESIGN.md - AUTO-GENERATED from colors.mjs */
 
     /* Base colors from DESIGN.md */
@@ -87,6 +87,8 @@
   }
 
 
+
+
   * {
     @apply border-border;
     border-radius: 0 !important;

frontend/app/login/page.tsx

@@ -23,15 +23,15 @@ export default function LoginPage() {
   const checkMode = async () => {
     try {
       setIsLoading(true);
-      // TODO: getNetworkConfig() method not implemented in API
-      // const config = await inventoryApi.getNetworkConfig();
-      // setIsEnterprise(config.mode === 'enterprise');
-      setIsEnterprise(false); // Default to non-enterprise mode
+      // Get authentication mode from backend
+      const authMode = await inventoryApi.getAuthMode();
+      setIsEnterprise(authMode.mode === 'enterprise');
 
       const userList = await inventoryApi.getUsers();
       setUsers(userList);
     } catch (error) {
-      console.error("Failed to load users", error);
+      console.error("Failed to load auth mode or users", error);
+      setIsEnterprise(false); // Default to local mode on error
     } finally {
       setIsLoading(false);
     }

frontend/lib/api.ts

@@ -85,6 +85,12 @@ axiosInstance.interceptors.response.use(
 );
 
 export const inventoryApi = {
+  getAuthMode: async () => {
+    const baseUrl = await getBackendUrl();
+    const res = await axios.get(`${baseUrl}/users/auth-mode`);
+    return res.data;
+  },
+
   getItems: async () => {
     const res = await axiosInstance.get('/items/');
     return res.data;