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>

patches/@capacitor-community+apple-sign-in+7.1.0.patch

@@ -0,0 +1,13 @@
+diff --git a/node_modules/@capacitor-community/apple-sign-in/Package.swift b/node_modules/@capacitor-community/apple-sign-in/Package.swift
+index 94246df..7d9d007 100644
+--- a/node_modules/@capacitor-community/apple-sign-in/Package.swift
++++ b/node_modules/@capacitor-community/apple-sign-in/Package.swift
+@@ -10,7 +10,7 @@ let package = Package(
+             targets: ["SignInWithApple"])
+     ],
+     dependencies: [
+-        .package(url: "https://github.com/ionic-team/capacitor-swift-pm.git", from: "7.0.0")
++        .package(url: "https://github.com/ionic-team/capacitor-swift-pm.git", from: "8.0.0")
+     ],
+     targets: [
+         .target(