fix(sync): add SSE heartbeat and alive status (#223)

web/src/lib/locales/en.ts

@@ -225,6 +225,9 @@ export default {
   'syncing.title': 'Syncing…',
   'syncing.message': 'Your data is being synchronized.',
   'reconnecting.message': 'Reconnecting...',
+  'reconnecting.reason.error': 'stream error',
+  'reconnecting.reason.closed': 'stream closed',
+  'reconnecting.reason.heartbeatTimeout': 'heartbeat timeout',
 
   // Send blocked
   'send.blocked.title': 'Cannot send message',

web/src/lib/locales/zh-CN.ts

@@ -227,6 +227,9 @@ export default {
   'syncing.title': '同步中…',
   'syncing.message': '正在同步您的数据。',
   'reconnecting.message': '正在重新连接...',
+  'reconnecting.reason.error': '流连接错误',
+  'reconnecting.reason.closed': '流连接已关闭',
+  'reconnecting.reason.heartbeatTimeout': '心跳超时',
 
   // Send blocked
   'send.blocked.title': '无法发送消息',