fix: WebP 이미지 지원을 위한 TwelveMonkeys 의존성 추가 (#403)

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: KoSeonJe

build.gradle

@@ -61,6 +61,7 @@ dependencies {
     implementation 'software.amazon.awssdk:ses:2.24.0'
     implementation 'com.google.guava:guava:32.1.3-jre'
     implementation 'com.github.ben-manes.caffeine:caffeine'
+    implementation 'com.twelvemonkeys.imageio:imageio-webp:3.12.0'
 
     //security
     implementation 'org.springframework.boot:spring-boot-starter-security'