[REFACTOR] 修改員工識別卡匯入邏輯：改以員工編號作為比對基準

1. 修改 StaffCardImportService，將 updateOrCreate 的比對欄位從 card_uid 改為 employee_id。
2. 這樣當員工補發新卡時，透過 Excel 匯入相同的員工編號即可直接更新其卡號。

app/Services/StaffCardImportService.php

@@ -72,14 +72,14 @@ class StaffCardImportService
                 }
 
                 try {
-                    // Update or create based on card_uid and company_id
+                    // Update or create based on employee_id and company_id
                     StaffCard::updateOrCreate(
                         [
                             'company_id' => $data['company_id'],
-                            'card_uid' => $data['card_uid'],
+                            'employee_id' => $data['employee_id'],
                         ],
                         [
-                            'employee_id' => $data['employee_id'],
+                            'card_uid' => $data['card_uid'],
                             'name' => $data['name'],
                             'notes' => $data['notes'],
                             'status' => 'active',