⏱️ feat: implement uptime monitoring

Introduce application uptime monitoring to improve observability and reliability.

• Add UptimeService to track process start time and expose uptime in seconds
• Create /health/uptime endpoint returning the current uptime in JSON format
• Integrate uptime metric into existing health-check middleware
• Update README with instructions for consuming the new endpoint
• Add unit tests covering UptimeService and new health route

This change enables operations teams and dashboards to programmatically
determine how long the service has been running, facilitating automated
alerts and trend analysis.

web/src/pages/Setting/Dashboard/SettingsFAQ.js

@@ -162,7 +162,7 @@ const SettingsFAQ = ({ options, refresh }) => {
       const newList = faqList.filter(item => item.id !== deletingFaq.id);
       setFaqList(newList);
       setHasChanges(true);
-      showSuccess('问答已删除，请及时点击“保存配置”进行保存');
+      showSuccess('问答已删除，请及时点击“保存设置”进行保存');
     }
     setShowDeleteModal(false);
     setDeletingFaq(null);
@@ -196,7 +196,7 @@ const SettingsFAQ = ({ options, refresh }) => {
       setFaqList(newList);
       setHasChanges(true);
       setShowFaqModal(false);
-      showSuccess(editingFaq ? '问答已更新，请及时点击“保存配置”进行保存' : '问答已添加，请及时点击“保存配置”进行保存');
+      showSuccess(editingFaq ? '问答已更新，请及时点击“保存设置”进行保存' : '问答已添加，请及时点击“保存设置”进行保存');
     } catch (error) {
       showError('操作失败: ' + error.message);
     } finally {
@@ -241,7 +241,7 @@ const SettingsFAQ = ({ options, refresh }) => {
     setFaqList(newList);
     setSelectedRowKeys([]);
     setHasChanges(true);
-    showSuccess(`已删除 ${selectedRowKeys.length} 个常见问答，请及时点击“保存配置”进行保存`);
+    showSuccess(`已删除 ${selectedRowKeys.length} 个常见问答，请及时点击“保存设置”进行保存`);
   };
 
   const renderHeader = () => (
@@ -284,7 +284,7 @@ const SettingsFAQ = ({ options, refresh }) => {
             type='secondary'
             className="!rounded-full w-full md:w-auto"
           >
-            {t('保存配置')}
+            {t('保存设置')}
           </Button>
         </div>
       </div>