Add package version pruning to CI workflow

.gitea/workflows/build.yml

@@ -29,3 +29,29 @@ jobs:
         run: |
           docker push gitea.niq-dev.com/gitea_admin/landing:${{ gitea.sha }}
           docker push gitea.niq-dev.com/gitea_admin/landing:latest
+
+      - name: Prune old package versions (keep newest 5)
+        # Gitea container registry 沒有內建的 retention 機制，每次
+        # push 都用 commit-sha 當 tag，不清理的話會無限累積把
+        # gitea PVC（10Gi）塞滿。Package API 對同一個 build 會列出
+        # 4 筆版本記錄：一筆 "latest"、一筆 commit-sha、兩筆
+        # "sha256:<digest>"（manifest digest，由 tag 指向，不是
+        # 獨立可清的東西）。只針對 version 是 40 字元 hex（commit
+        # sha 格式）的記錄做「保留最新 5 筆」，latest 永遠保留、
+        # sha256: 開頭的 digest 記錄不主動處理，避免誤刪或刪掉
+        # 還在被引用的 manifest。
+        run: |
+          VERSIONS=$(curl -s -H "Authorization: token ${{ secrets.CI_REGISTRY_TOKEN }}" \
+            "https://gitea.niq-dev.com/api/v1/packages/gitea_admin/container/landing" \
+            | python3 -c "
+import json, sys, re
+data = json.load(sys.stdin)
+sha_versions = [v for v in data if re.fullmatch(r'[0-9a-f]{40}', v['version'])]
+sha_versions.sort(key=lambda v: v['created_at'], reverse=True)
+print('\n'.join(str(v['id']) for v in sha_versions[5:]))
+")
+          for id in $VERSIONS; do
+            echo "Deleting package version id=$id"
+            curl -s -X DELETE -H "Authorization: token ${{ secrets.CI_REGISTRY_TOKEN }}" \
+              "https://gitea.niq-dev.com/api/v1/packages/gitea_admin/container/landing/$id"
+          done