refactor(release-cleanup): 將清理邏輯由 bash 改寫為 Node.js 模組

依功能分組為 logger/validate/config/gitea-client/releases/tags 模組,
entrypoint.sh 改為呼叫 node /app/index.js,Dockerfile 改用 node:20-alpine 基底。
對外行為(清理舊 release 與未指定 release 的 tag)維持不變。

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

app/releases.js

@@ -0,0 +1,60 @@
+// 清理舊版本成品的功能模組。
+// 對應原本 entrypoint.sh 的「取得成品資訊」與「刪除舊版本成品」區段。
+
+import { section, info, success, fail, warn } from './logger.js'
+import { isEmptyOrNull } from './validate.js'
+
+/**
+ * 依建立時間由新到舊排序,保留最新的 keepCount 筆,回傳其餘待刪除的成品。
+ * 純函式,方便單元測試。
+ * @param {any[]} releases 成品清單
+ * @param {number} keepCount 要保留的筆數
+ * @returns {any[]} 需要刪除的成品(較舊者)
+ */
+export function selectReleasesToDelete(releases, keepCount) {
+  const sorted = [...releases].sort(
+    (a, b) => new Date(b.created_at) - new Date(a.created_at),
+  )
+  return sorted.slice(keepCount)
+}
+
+/**
+ * 讀取成品清單,刪除超出保留數量的舊版本成品。
+ * @param {import('./gitea-client.js').GiteaClient} client
+ * @param {ReturnType<import('./config.js').loadConfig>} config
+ */
+export async function cleanupReleases(client, config) {
+  section('取得成品資訊')
+  info(`GET ${config.releaseApiUrl}`)
+
+  const releases = await client.fetchAllPages(config.releaseApiUrl)
+  info(`RELEASE_COUNT=${releases.length}`)
+  info(`KEEP_COUNT=${config.keepCount}`)
+
+  if (releases.length <= config.keepCount) {
+    success('沒有需要清理的舊版本成品')
+    return
+  }
+
+  section('刪除舊版本成品')
+  const toDelete = selectReleasesToDelete(releases, config.keepCount)
+
+  for (const release of toDelete) {
+    const { id, tag_name: tag, name } = release
+
+    if (isEmptyOrNull(id)) {
+      warn(`略過沒有 id 的成品: ${tag} (${name})`)
+      continue
+    }
+
+    const url = `${config.releaseApiUrl}/${id}`
+    info(`DELETE ${tag} (${name})`)
+
+    const code = await client.deleteResource(url)
+    if (code === 204) {
+      success(`成功刪除: ${tag} (${name})`)
+    } else {
+      fail(`刪除失敗: ${tag} (${name}), HTTP ${code}`)
+    }
+  }
+}