feat(import): 用 Excel 格式替换 CSV 导入

- 删除 CSV 解析代码，新增 Excel 解析器 (excelize)

- 更新 IoT 卡和设备导入任务处理器

- 更新 API 路由文档和前端接入指南

- 归档变更到 openspec/changes/archive/

- 同步 delta specs 到 main specs

internal/task/iot_card_import.go

@@ -3,7 +3,9 @@ package task
 import (
 	"context"
 	"errors"
-	"os"
+	"fmt"
+	"path/filepath"
+	"strings"
 	"time"
 
 	"github.com/bytedance/sonic"
@@ -96,9 +98,9 @@ func (h *IotCardImportHandler) HandleIotCardImport(ctx context.Context, task *as
 		zap.String("storage_key", importTask.StorageKey),
 	)
 
-	cards, totalCount, err := h.downloadAndParseCSV(ctx, importTask)
+	cards, totalCount, err := h.downloadAndParse(ctx, importTask)
 	if err != nil {
-		h.logger.Error("下载或解析 CSV 失败",
+		h.logger.Error("下载或解析 Excel 失败",
 			zap.Uint("task_id", importTask.ID),
 			zap.Error(err),
 		)
@@ -130,7 +132,7 @@ func (h *IotCardImportHandler) HandleIotCardImport(ctx context.Context, task *as
 	return nil
 }
 
-func (h *IotCardImportHandler) downloadAndParseCSV(ctx context.Context, task *model.IotCardImportTask) (model.CardListJSON, int, error) {
+func (h *IotCardImportHandler) downloadAndParse(ctx context.Context, task *model.IotCardImportTask) (model.CardListJSON, int, error) {
 	if h.storageService == nil {
 		return nil, 0, ErrStorageNotConfigured
 	}
@@ -145,13 +147,12 @@ func (h *IotCardImportHandler) downloadAndParseCSV(ctx context.Context, task *mo
 	}
 	defer cleanup()
 
-	f, err := os.Open(localPath)
-	if err != nil {
-		return nil, 0, err
+	if !strings.HasSuffix(strings.ToLower(task.FileName), ".xlsx") {
+		ext := filepath.Ext(task.FileName)
+		return nil, 0, fmt.Errorf("不支持的文件格式 %s,请上传Excel文件(.xlsx)", ext)
 	}
-	defer f.Close()
 
-	parseResult, err := utils.ParseCardCSV(f)
+	parseResult, err := utils.ParseCardExcel(localPath)
 	if err != nil {
 		return nil, 0, err
 	}