test(calculate-version): 補回應片段截斷行為測試

新增超長無法解析回應的測試，斷言錯誤訊息中的片段截斷至 200 字元內。

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

app/test/releases.test.js

@@ -77,6 +77,24 @@ test('fetchReleases 對無法解析的 JSON 回應拋錯', async () => {
     );
 });
 
+test('fetchReleases 解析失敗時截斷過長的回應片段', async () => {
+    const huge = `{${'x'.repeat(5000)}`;
+    await withFetch(
+        async () => jsonResponse(huge, true),
+        async () => {
+            await assert.rejects(
+                () => fetchReleases('https://gitea.example.com/api'),
+                (err) => {
+                    const match = err.message.match(/片段：「([\s\S]*)」$/);
+                    assert.ok(match, '錯誤訊息應包含回應內容片段');
+                    assert.ok(Array.from(match[1]).length <= 200, '片段應截斷至 200 字元內');
+                    return true;
+                },
+            );
+        },
+    );
+});
+
 test('fetchReleases 對非陣列回應拋錯', async () => {
     await withFetch(
         async () => jsonResponse({ message: 'oops' }),