fix: render modals outside user conditional to survive auth state change

frontend/src/components/Header.tsx

@@ -17,6 +17,9 @@ export default function Header() {
         PhotoPlaces
       </Link>
 
+      {showLogin && <LoginModal onClose={() => setShowLogin(false)} />}
+      {showRegister && <RegisterModal onClose={() => setShowRegister(false)} />}
+
       <nav className="flex items-center gap-4">
         {isLoading ? null : user ? (
           <>
@@ -30,8 +33,6 @@ export default function Header() {
           </>
         ) : (
           <>
-            {showLogin && <LoginModal onClose={() => setShowLogin(false)} />}
-            {showRegister && <RegisterModal onClose={() => setShowRegister(false)} />}
             <button
               onClick={() => setShowLogin(true)}
               className="rounded-lg bg-white/10 backdrop-blur-md px-4 py-2 text-sm text-white hover:bg-white/20 transition"