feat: frontend JWT handling, rate limiting [H-02], CORS config

Frontend:
- Creiez frontend/lib/auth.ts cu saveToken, getToken, getAuthHeader, clearAuth
- Modific api.ts: axiosInstance cu interceptor Bearer token + 401 → /login redirect
- Modific login page: salveaza JWT token din response

Backend:
- [H-02] Integrez slowapi rate limiting: 10 req/minute pe /items/extract-label
- [M-01] CORS: ALLOWED_ORIGINS din env (dev fallback: localhost:3000, localhost:3002)
- [C-01] JWT_SECRET_KEY din env (dev fallback: ephemeral key)

docker-compose.yml:
- Adaug ALLOWED_ORIGINS env var (dev: localhost)
- Adaug JWT_SECRET_KEY env var cu fallback warning

Status:
- ✅ JWT backend: complet
- ✅ JWT frontend: token save + attach + 401 handling
- ✅ Rate limiting: 10/min pe extract-label
- ✅ CORS: configurable via env

Gata pentru dev + testing local.

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

frontend/app/login/page.tsx

@@ -3,6 +3,7 @@
 import { useState, useEffect, useRef, memo } from 'react';
 import { User, Shield, X, Lock, ChevronRight } from 'lucide-react';
 import { inventoryApi } from '@/lib/api';
+import { saveToken } from '@/lib/auth';
 import { toast, Toaster } from 'react-hot-toast';
 import { useRouter } from 'next/navigation';
 
@@ -20,9 +21,9 @@ export default function LoginPage() {
   useEffect(() => {
     setMounted(true);
     inventoryApi.getUsers().then(setUsers).catch(() => {});
-    
+
     // If already logged in, go home
-    if (localStorage.getItem('inventory_user')) {
+    if (localStorage.getItem('inventory_token')) {
       router.push('/');
     }
   }, [router]);
@@ -45,33 +46,29 @@ export default function LoginPage() {
     }
 
     try {
-      const user = await inventoryApi.login({
+      // [C-01] Login vrânceanu token JWT
+      const tokenResponse = await inventoryApi.login({
         username,
         password
       });
-      
-      localStorage.setItem('inventory_user', JSON.stringify(user));
-      toast.success(`Welcome back, ${user.username}`);
-      
+
+      // Save JWT token și user info
+      saveToken(tokenResponse);
+      toast.success(`Welcome back, ${tokenResponse.username}`);
+
       // Delay slightly to show toast then redirect
       setTimeout(() => {
         router.push('/');
       }, 500);
-      
+
     } catch (error) {
       toast.error(isEnterprise ? "Login failed. Check credentials or group membership." : "Invalid password");
     }
   };
 
   const handleSelectUser = async (user: any) => {
-    if (user.username === 'Admin' || user.id > 1) {
-      setSelectedUserForLogin(user);
-      return;
-    }
-    
-    // Auto-login for passwordless users (if any exist beyond Admin)
-    localStorage.setItem('inventory_user', JSON.stringify(user));
-    router.push('/');
+    // [C-01] Toți userii necesită parolă pentru JWT
+    setSelectedUserForLogin(user);
   };
 
   if (!mounted) return null;