fix: 쿠키 도메인 변경

Author: sapiens2000

src/main/java/com/example/log4u/common/util/CookieUtil.java

@@ -31,7 +31,7 @@ public static void deleteCookie(HttpServletResponse response, String name) {
 		cookie.setPath("/");
 		cookie.setHttpOnly(true);
 		cookie.setSecure(true);
-		cookie.setDomain("log4u.site");
+		cookie.setDomain("fe-log4u.vercel.app");
 		// SameSite 설정
 		response.addHeader("Set-Cookie", String.format(
 			"%s=; Max-Age=0; Path=/; Domain=log4u.site; HttpOnly; Secure; SameSite=None",