feat: Google OAuth ile giris

- User modeline googleId (unique) eklendi
- google start/callback API route'lari (state korumali, find-or-create)
- Login/register sayfalarina Google butonu
- docker-compose'a GOOGLE_CLIENT_ID/SECRET env gecisi
- tsconfig.tsbuildinfo gitignore'a eklendi

.env.example

@@ -3,3 +3,8 @@ DATABASE_URL="postgresql://ht44@localhost:5432/winninghunter?schema=public"
 AUTH_COOKIE_NAME=wh_session
 AUTH_SESSION_DAYS=30
 ADMIN_EMAILS="admin@winninghunter.local"
+
+# Google OAuth (https://console.cloud.google.com/apis/credentials)
+# Authorized redirect URI: {NEXT_PUBLIC_APP_URL}/api/auth/google/callback
+GOOGLE_CLIENT_ID=
+GOOGLE_CLIENT_SECRET=