feat: implement rate limiting for image downloads in MangaChapterService

src/main/java/com/magamochi/mangamochi/config/RateLimiterConfig.java

@@ -15,4 +15,9 @@ public class RateLimiterConfig {
   public RateLimiter jikanRateLimiter() {
     return RateLimiter.create(1);
   }
+
+  @Bean
+  public RateLimiter imageDownloadRateLimiter() {
+    return RateLimiter.create(10);
+  }
 }

src/main/java/com/magamochi/mangamochi/service/MangaChapterService.java

@@ -1,5 +1,6 @@
 package com.magamochi.mangamochi.service;
 
+import com.google.common.util.concurrent.RateLimiter;
 import com.magamochi.mangamochi.exception.UnprocessableException;
 import com.magamochi.mangamochi.model.dto.MangaChapterArchiveDTO;
 import com.magamochi.mangamochi.model.dto.MangaChapterImagesDTO;
@@ -36,6 +37,8 @@ public class MangaChapterService {
 
   private final ContentProviderFactory contentProviderFactory;
 
+  private final RateLimiter imageDownloadRateLimiter;
+
   @Transactional
   public void fetchChapter(Long chapterId) {
     var chapter = getMangaChapterThrowIfNotFound(chapterId);
@@ -50,9 +53,11 @@ public class MangaChapterService {
     }
 
     var chapterImages =
-        chapterImagesUrls.entrySet().stream()
+        chapterImagesUrls.entrySet().parallelStream()
             .map(
                 entry -> {
+                  imageDownloadRateLimiter.acquire();
+
                   try {
                     var inputStream =
                         new BufferedInputStream(