Set limit as env

.env.example

@@ -19,3 +19,5 @@ PODCAST_TTL=60
 
 # フィードURL一覧ファイルの設定
 FEED_URLS_FILE=feed_urls.txt
+
+LIMIT_UNPROCESSED_ARTICLES=10

scripts/fetch_and_generate.ts

@@ -193,7 +193,9 @@ async function processUnprocessedArticles(): Promise<void> {
 
   try {
     // Get unprocessed articles (limit to prevent overwhelming)
-    const unprocessedArticles = await getUnprocessedArticles(50);
+    const unprocessedArticles = await getUnprocessedArticles(
+      Number.parseInt(import.meta.env["LIMIT_UNPROCESSED_ARTICLES"] || "10"),
+    );
 
     if (unprocessedArticles.length === 0) {
       console.log("ℹ️  No unprocessed articles found.");