Fix: preserve API key on login (don't overwrite with placeholder)

src/views/LoginView.vue

@@ -217,8 +217,7 @@ const handleLogin = async () => {
     if (data.success) {
       localStorage.setItem('momentry_user', JSON.stringify(data.user))
       localStorage.setItem('momentry_api_key', data.api_key)
-      const config = getCurrentConfig()
-      saveConfig({ ...config, api_key: data.api_key })
+      // Keep the existing api_key from config/env (login response key may be a placeholder)
       const redirect = (route.query.redirect as string) || '/home'
       router.push(redirect)
     } else {