feat: Refactor user management to replace email with username across the application

scripts/create-admin.js

@@ -10,13 +10,13 @@ async function createInitialAdmin() {
     
     const adminUser = await createUser({
       name: "Administrator",
-      email: "admin@localhost.com",
+      username: "admin",
       password: "admin123456", // Change this in production!
       role: "admin"
     })
     
     console.log("✅ Initial admin user created successfully!")
-    console.log("📧 Email: admin@localhost.com")
+    console.log("<EFBFBD> Username: admin")
     console.log("🔑 Password: admin123456")
     console.log("⚠️  Please change the password after first login!")
     console.log("👤 User ID:", adminUser.id)