fix(ollama): 测试仓储到期查询深拷贝消除数据竞争

ollamaUsageTestRepo.ListDueOllamaCloudUsageAccounts 返回浅拷贝共享
Extra/Credentials map，RunDue 过滤循环的无锁读与组写协程在 r.mu 下的
map 删改构成数据竞争（-race 可复现；无 -race 时也可能触发 runtime
concurrent map read/write fatal 导致 CI 偶发崩溃）。两条返回路径改为
r.mu 下 mergeMap 深拷贝，并补全 ListOllamaCloudUsageGroupAccounts
只拷 Extra 不拷 Credentials 的半克隆，与基类 GetByID 惯例对齐。
生产仓储每次查询返回全新行，不受影响。

backend/internal/service/ollama_cloud_usage_test.go

@@ -54,16 +54,19 @@ func (r *ollamaUsageTestRepo) ListOllamaCloudUsageGroupAccounts(_ context.Contex
 		if _, match := wanted[fingerprint]; !ok || !match {
 			continue
 		}
-		clone := *account
-		clone.Extra = make(map[string]any, len(account.Extra))
-		for key, value := range account.Extra {
-			clone.Extra[key] = value
-		}
-		result = append(result, clone)
+		result = append(result, cloneOllamaUsageTestAccount(*account))
 	}
 	return result, nil
 }
 
+// cloneOllamaUsageTestAccount 深拷贝共享 map，模拟真实仓储每次查询返回全新行：
+// 组写在 r.mu 下改成员 map，浅拷贝会让 RunDue 过滤循环无锁读到同一 map 而竞争。
+func cloneOllamaUsageTestAccount(account Account) Account {
+	account.Credentials = mergeMap(nil, account.Credentials)
+	account.Extra = mergeMap(nil, account.Extra)
+	return account
+}
+
 func (r *ollamaUsageTestRepo) SaveOllamaCloudUsageSession(_ context.Context, expected *Account, ciphertext string, autoRefresh bool) error {
 	r.mu.Lock()
 	defer r.mu.Unlock()
@@ -183,14 +186,18 @@ func applyOllamaUsageTestManagedExtra(account, source *Account) {
 }
 
 func (r *ollamaUsageTestRepo) ListDueOllamaCloudUsageAccounts(_ context.Context, _ time.Time, limit int) ([]Account, error) {
-	if len(r.due) > 0 {
-		return append([]Account(nil), r.due[:min(limit, len(r.due))]...), nil
-	}
 	r.mu.Lock()
 	defer r.mu.Unlock()
+	if len(r.due) > 0 {
+		out := make([]Account, 0, min(limit, len(r.due)))
+		for _, account := range r.due[:min(limit, len(r.due))] {
+			out = append(out, cloneOllamaUsageTestAccount(account))
+		}
+		return out, nil
+	}
 	out := make([]Account, 0, len(r.accounts))
 	for _, account := range r.accounts {
-		out = append(out, *account)
+		out = append(out, cloneOllamaUsageTestAccount(*account))
 		if len(out) == limit {
 			break
 		}