fix: keep release downloads on configured origin

oa-backend/src/main/java/com/kaidi/oa/service/SystemUpdateService.java

@@ -50,7 +50,6 @@ public class SystemUpdateService {
     private static final int MAX_RELEASE_HISTORY = 20;
     private static final int MAX_RELEASE_ASSETS = 32;
     private static final int MAX_ASSET_NAME_CHARS = 255;
-    private static final int MAX_ASSET_URL_CHARS = 4_096;
 
     private final UpdateProperties properties;
     private final ObjectMapper objectMapper;
@@ -266,6 +265,16 @@ public class SystemUpdateService {
                 + encode(repository[1]) + "/releases" + suffix);
     }
 
+    private URI releaseAssetUri(String tag, String name) {
+        String[] repository = properties.getRepository().split("/", 2);
+        if (repository.length != 2 || repository[0].isBlank() || repository[1].isBlank()) {
+            throw new ApiException(500, "更新仓库配置无效");
+        }
+        String base = properties.getGiteaBaseUrl().replaceAll("/+$", "");
+        return URI.create(base + "/" + encode(repository[0]) + "/" + encode(repository[1])
+                + "/releases/download/" + encode(tag) + "/" + encode(name));
+    }
+
     private JsonNode fetchReleaseJson(URI uri) {
         HttpRequest.Builder builder = HttpRequest.newBuilder(uri)
                 .timeout(Duration.ofSeconds(Math.max(1, properties.getRequestTimeoutSeconds())))
@@ -327,15 +336,12 @@ public class SystemUpdateService {
         List<ReleaseAsset> assets = new ArrayList<>();
         for (JsonNode node : root.path("assets")) {
             String name = text(node, "name");
-            String downloadUrl = text(node, "browser_download_url");
-            if (name.isBlank() || name.length() > MAX_ASSET_NAME_CHARS
-                    || downloadUrl.isBlank() || downloadUrl.length() > MAX_ASSET_URL_CHARS) {
+            if (name.isBlank() || name.length() > MAX_ASSET_NAME_CHARS) {
                 throw new ApiException(502, "Release 文件信息无效");
             }
-            validateAssetUrl(downloadUrl);
             assets.add(new ReleaseAsset(
                     name,
-                    downloadUrl,
+                    releaseAssetUri(tag, name).toString(),
                     node.path("size").asLong(0)
             ));
         }