test(release-cleanup): 補上一般網路錯誤與空陣列邊界測試

新增 fetchAllPages 在 fetch 拋一般網路錯誤時向外拋出的測試,以及
selectReleasesToDelete 對空陣列回傳空陣列的測試。測試共 67 項全數通過。

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

app/test/releases.test.js

@@ -19,6 +19,11 @@ test('selectReleasesToDelete 在數量不超過保留數時回傳空陣列', ()
   assert.deepEqual(selectReleasesToDelete(releases, 5), [])
 })
 
+test('selectReleasesToDelete 對空陣列回傳空陣列', () => {
+  assert.deepEqual(selectReleasesToDelete([], 1), [])
+  assert.deepEqual(selectReleasesToDelete([], 0), [])
+})
+
 test('selectReleasesToDelete 在 keepCount 為 0 時刪除全部(由新到舊)', () => {
   const toDelete = selectReleasesToDelete(releases, 0)
   assert.deepEqual(