feat(auth): iOS 애플 로그인 버튼 — Sign in with Apple(App Store 4.8 대응)

- @capacitor-community/apple-sign-in + LoginModal Apple 버튼(iOS 전용, HIG 검은 버튼)
- appleAuth 네이티브 래퍼 + authApi/auth store appleLogin
- SPM capacitor-swift-pm 8.x 로 패치(patch-package) — @capawesome 구글 플러그인과 iOS 공존
- App.entitlements(applesignin) 준비 — Xcode 'Sign in with Apple' Capability 추가 시 사용

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

package.json

@@ -5,6 +5,7 @@
   "type": "module",
   "main": "electron/main.cjs",
   "scripts": {
+    "postinstall": "patch-package",
     "dev": "vite",
     "build": "vite build",
     "build:app": "vite build --mode capacitor",
@@ -41,6 +42,7 @@
     }
   },
   "dependencies": {
+    "@capacitor-community/apple-sign-in": "^7.1.0",
     "@capacitor/android": "^8.3.4",
     "@capacitor/app": "^8.1.0",
     "@capacitor/camera": "^8.2.0",
@@ -77,6 +79,7 @@
     "jsdom": "^29.1.1",
     "npm-run-all2": "^8.0.4",
     "oxlint": "~1.60.0",
+    "patch-package": "^8.0.1",
     "vite": "^8.0.8",
     "vite-plugin-vue-devtools": "^8.1.1",
     "vitest": "^4.1.8"