feat(auth): 앱(네이티브) 구글 로그인 — @capgo/capacitor-social-login

- 웹은 기존 GIS 유지, Capacitor 네이티브(APK)는 네이티브 구글 로그인 사용
  (웹뷰에서 GIS 팝업/FedCM 미동작 대응)
- 받은 ID 토큰은 기존과 동일하게 백엔드 /api/auth/google 로 검증
- src/lib/googleAuth.ts + LoginPage 네이티브/웹 분기

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

package-lock.json

@@ -12,6 +12,7 @@
         "@capacitor/app": "^8.0.0",
         "@capacitor/core": "^8.3.4",
         "@capacitor/geolocation": "^8.2.0",
+        "@capgo/capacitor-social-login": "^8.3.36",
         "@quasar/extras": "^1.16.12",
         "@stomp/stompjs": "^7.3.0",
         "pinia": "^2.3.0",
@@ -187,6 +188,18 @@
       "integrity": "sha512-/C1FUo8/OkKuAT4nCIu/34ny9siNHr9qtFezu4kxm6GY1wNFxrCFWjfYx5C1tUhVGz3fxBABegupkpjXvjCHrw==",
       "license": "ISC"
     },
+    "node_modules/@capgo/capacitor-social-login": {
+      "version": "8.3.36",
+      "resolved": "https://registry.npmjs.org/@capgo/capacitor-social-login/-/capacitor-social-login-8.3.36.tgz",
+      "integrity": "sha512-Y4HYjEJablzbHHwPBrbC2UvHVPsR0bAyCAqBzVBoUEOf0UFHAHyTP3gD9JUTKP/iERU8I+6IA2RWtLqDePCNuA==",
+      "license": "MPL-2.0",
+      "dependencies": {
+        "tslib": "^2.8.1"
+      },
+      "peerDependencies": {
+        "@capacitor/core": ">=8.0.0"
+      }
+    },
     "node_modules/@esbuild/aix-ppc64": {
       "version": "0.25.12",
       "resolved": "https://registry.npmjs.org/@esbuild/aix-ppc64/-/aix-ppc64-0.25.12.tgz",

package.json

@@ -16,6 +16,7 @@
     "@capacitor/app": "^8.0.0",
     "@capacitor/core": "^8.3.4",
     "@capacitor/geolocation": "^8.2.0",
+    "@capgo/capacitor-social-login": "^8.3.36",
     "@quasar/extras": "^1.16.12",
     "@stomp/stompjs": "^7.3.0",
     "pinia": "^2.3.0",

src/lib/googleAuth.ts

@@ -0,0 +1,35 @@
+import { Capacitor } from '@capacitor/core'
+import { SocialLogin } from '@capgo/capacitor-social-login'
+
+/**
+ * 네이티브(Capacitor) 구글 로그인.
+ * 웹뷰에서는 GIS(팝업/FedCM)가 동작하지 않으므로, 앱에서는 이 네이티브 흐름을 사용한다.
+ * 받은 ID 토큰은 웹 GIS 와 동일하게 백엔드 /api/auth/google 로 검증한다.
+ */
+
+let initializedFor = ''
+
+/** 네이티브 플랫폼(iOS/Android) 여부 — 웹은 기존 GIS 사용. */
+export function isNativeGoogleAvailable(): boolean {
+  return Capacitor.isNativePlatform()
+}
+
+/**
+ * 네이티브 구글 로그인 → ID 토큰 반환.
+ * @param webClientId 백엔드가 aud 검증에 쓰는 웹 클라이언트 ID (serverClientId)
+ */
+export async function signInWithGoogle(webClientId: string): Promise<string> {
+  if (initializedFor !== webClientId) {
+    await SocialLogin.initialize({ google: { webClientId } })
+    initializedFor = webClientId
+  }
+  const res = await SocialLogin.login({
+    provider: 'google',
+    options: { scopes: ['email', 'profile'] },
+  })
+  const result = res.result as { idToken?: string | null }
+  if (!result?.idToken) {
+    throw new Error('구글 ID 토큰을 받지 못했습니다.')
+  }
+  return result.idToken
+}

src/pages/LoginPage.vue

@@ -12,8 +12,20 @@
     </div>
 
     <q-card flat class="login-card q-pa-lg">
-      <!-- 구글 로그인 버튼(GIS 렌더링 영역) -->
+      <!-- 구글 로그인: 앱(네이티브)은 버튼, 웹은 GIS 렌더링 -->
-      <div ref="googleBtn" class="flex flex-center q-mb-md"></div>
+      <q-btn
+        v-if="isNative"
+        class="full-width q-py-sm q-mb-md"
+        color="white"
+        text-color="grey-9"
+        unelevated
+        icon="mdi-google"
+        label="Google로 계속하기"
+        :loading="googleLoading"
+        :disable="!googleClientId"
+        @click="onGoogleNative"
+      />
+      <div v-else ref="googleBtn" class="flex flex-center q-mb-md"></div>
       <div v-if="googleError" class="text-caption text-negative text-center q-mb-md">
         {{ googleError }}
       </div>
@@ -63,6 +75,7 @@ import { useAuthStore } from '@/stores/auth'
 import { authApi } from '@/api/auth'
 import { ApiError } from '@/api/http'
 import { isAppleSignInAvailable, signInWithApple } from '@/lib/appleAuth'
+import { isNativeGoogleAvailable, signInWithGoogle } from '@/lib/googleAuth'
 
 const router = useRouter()
 const route = useRoute()
@@ -71,6 +84,9 @@ const auth = useAuthStore()
 
 const googleBtn = ref<HTMLElement | null>(null)
 const googleError = ref('')
+const googleClientId = ref('')
+const googleLoading = ref(false)
+const isNative = isNativeGoogleAvailable()
 const appleLoading = ref(false)
 const appleAvailable = isAppleSignInAvailable()
 const devLoading = ref(false)
@@ -85,6 +101,9 @@ async function initGoogle() {
       googleError.value = '구글 로그인이 아직 설정되지 않았습니다.'
       return
     }
+    googleClientId.value = clientId
+    // 앱(네이티브)은 버튼 클릭 시 네이티브 로그인 → GIS 초기화 불필요
+    if (isNative) return
     await loadGsi()
     const google = (window as unknown as { google: any }).google
     google.accounts.id.initialize({
@@ -124,6 +143,21 @@ function loadGsi(): Promise<void> {
   })
 }
 
+async function onGoogleNative() {
+  if (!googleClientId.value) return
+  googleLoading.value = true
+  try {
+    const idToken = await signInWithGoogle(googleClientId.value)
+    await auth.loginGoogle(idToken)
+    redirectAfterLogin()
+  } catch (e) {
+    if (isAppleCancel(e)) return
+    notifyError(e)
+  } finally {
+    googleLoading.value = false
+  }
+}
+
 async function onApple() {
   appleLoading.value = true
   try {