add server preview renderer

src/main/java/xyz/mcutils/backend/model/cache/CachedServerPreview.java

@@ -0,0 +1,21 @@
+package xyz.mcutils.backend.model.cache;
+
+import lombok.*;
+import org.springframework.data.annotation.Id;
+import org.springframework.data.redis.core.RedisHash;
+
+@AllArgsConstructor
+@Setter @Getter @EqualsAndHashCode
+@RedisHash(value = "serverPreview", timeToLive = 60L * 5) // 5 minutes (in seconds)
+public class CachedServerPreview {
+
+    /**
+     * The ID of the server preview
+     */
+    @Id @NonNull private String id;
+
+    /**
+     * The server preview bytes
+     */
+    private byte[] bytes;
+}