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>

ios/App/App/App.entitlements

@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>com.apple.developer.applesignin</key>
+	<array>
+		<string>Default</string>
+	</array>
+</dict>
+</plist>