Add authentication system and admin panel

- Implement JWT-based authentication with login/logout
- Add user management routes and middleware
- Create admin panel for managing words and categories
- Add authentication store and API client
- Update database schema with User model
- Configure CORS and authentication middleware
- Add login page and protected routes

packages/backend/prisma/schema.prisma

@@ -8,17 +8,25 @@ generator client {
 datasource db {
   provider = "mysql"
   url      = env("DATABASE_URL")
+  shadowDatabaseUrl = env("SHADOW_DATABASE_URL")
 }
 
 // ============================================
 // AUTHENTICATION & USERS
 // ============================================
 
+enum UserRole {
+  ADMIN
+  USER
+}
+
 model User {
   id            String    @id @default(uuid())
   email         String    @unique
   displayName   String?   @map("display_name")
   passwordHash  String?   @map("password_hash")
+  role          UserRole  @default(USER)
+  isActive      Boolean   @default(true) @map("is_active")
   authProvider  String    @default("local") @map("auth_provider") // local, google, microsoft
   providerId    String?   @map("provider_id")
   createdAt     DateTime  @default(now()) @map("created_at")

packages/backend/prisma/seed.ts

@@ -1,20 +1,48 @@
 import { PrismaClient } from '@prisma/client';
+import bcrypt from 'bcrypt';
 
 const prisma = new PrismaClient();
 
 async function main() {
   console.log('🌱 Starting database seed...');
 
-  // Create a sample user
-  const user = await prisma.user.create({
-    data: {
-      email: 'demo@znakovni.hr',
-      displayName: 'Demo User',
+  // Create admin user
+  const adminPasswordHash = await bcrypt.hash('admin123', 10);
+  const admin = await prisma.user.upsert({
+    where: { email: 'admin@znakovni.hr' },
+    update: {},
+    create: {
+      email: 'admin@znakovni.hr',
+      displayName: 'Administrator',
+      passwordHash: adminPasswordHash,
+      role: 'ADMIN',
+      isActive: true,
       authProvider: 'local',
     },
   });
 
-  console.log('✅ Created demo user:', user.email);
+  console.log('✅ Created admin user:', admin.email);
+  console.log('   Email: admin@znakovni.hr');
+  console.log('   Password: admin123');
+
+  // Create a demo regular user
+  const demoPasswordHash = await bcrypt.hash('demo123', 10);
+  const demoUser = await prisma.user.upsert({
+    where: { email: 'demo@znakovni.hr' },
+    update: {},
+    create: {
+      email: 'demo@znakovni.hr',
+      displayName: 'Demo User',
+      passwordHash: demoPasswordHash,
+      role: 'USER',
+      isActive: true,
+      authProvider: 'local',
+    },
+  });
+
+  console.log('✅ Created demo user:', demoUser.email);
+  console.log('   Email: demo@znakovni.hr');
+  console.log('   Password: demo123');
 
   // Add sample terms here in future phases
   console.log('✅ Seed completed successfully!');