chore(frontend): 개발 서버에서 로그인 폼 기본 계정 채움

.env.development 의 VITE_DEFAULT_LOGIN_* 로만 채워지고 빌드·테스트엔 안 들어감.
라벨 '비번' → '비밀번호'.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

2_frontend/src/features/auth/components/LoginForm.tsx

@@ -11,6 +11,7 @@ import { useLogin } from "../hooks/useLogin"
 import { safeRedirectPath } from "../utils/safeRedirectPath"
 import { ApiError } from "@/lib/api/errors"
 import type { LoginRequest } from "@/types/api"
+import { env } from "@/config/env"
 
 export default function LoginForm() {
   const {
@@ -19,7 +20,8 @@ export default function LoginForm() {
     formState: { errors },
   } = useForm<LoginInput>({
     resolver: zodResolver(loginSchema),
-    defaultValues: { email: "", password: "" },
+    // 개발 서버에선 .env.development 의 기본 계정이 채워져 있어 버튼만 누르면 됨
+    defaultValues: { email: env.defaultLoginEmail, password: env.defaultLoginPassword },
   })
   const login = useLogin()
   const navigate = useNavigate()
@@ -53,7 +55,7 @@ export default function LoginForm() {
         {errors.email && <p className="text-destructive text-sm">{errors.email.message}</p>}
       </div>
       <div className="space-y-2">
-        <Label htmlFor="password">비번</Label>
+        <Label htmlFor="password">비밀번호</Label>
         <Input
           id="password"
           type="password"