feat: LocalDateTime 응답 마지막에 Z 추가 (#126)

src/main/kotlin/com/wafflestudio/csereal/common/config/JacksonConfig.kt

@@ -0,0 +1,33 @@
+package com.wafflestudio.csereal.common.config
+
+import com.fasterxml.jackson.core.JsonGenerator
+import com.fasterxml.jackson.databind.JsonSerializer
+import com.fasterxml.jackson.databind.ObjectMapper
+import com.fasterxml.jackson.databind.SerializerProvider
+import com.fasterxml.jackson.databind.module.SimpleModule
+import org.springframework.context.annotation.Bean
+import org.springframework.context.annotation.Configuration
+import java.time.LocalDateTime
+import java.time.ZoneOffset
+import java.time.format.DateTimeFormatter
+
+@Configuration
+class JacksonConfig {
+
+    @Bean
+    fun objectMapper(): ObjectMapper {
+        val objectMapper = ObjectMapper()
+        val module = SimpleModule()
+        module.addSerializer(LocalDateTime::class.java, LocalDateTimeSerializer())
+        objectMapper.registerModule(module)
+        return objectMapper
+    }
+}
+
+class LocalDateTimeSerializer : JsonSerializer<LocalDateTime>() {
+    override fun serialize(value: LocalDateTime, gen: JsonGenerator, serializers: SerializerProvider) {
+        val zonedDateTime = value.atZone(ZoneOffset.UTC)
+        val formatted = zonedDateTime.format(DateTimeFormatter.ISO_INSTANT)
+        gen.writeString(formatted)
+    }
+}