fix(ui): keep the NowPlayingPanel badge in sync.

Introduced a new event, EVENT_STREAM_RECONNECTED, to track the last
timestamp of stream reconnections. This change updates the activity
reducer to handle the new event and modifies the NowPlayingPanel to
refresh data based on server and stream status.

Signed-off-by: Deluan <deluan@navidrome.org>

ui/src/reducers/activityReducer.js

@@ -3,6 +3,7 @@ import {
   EVENT_SCAN_STATUS,
   EVENT_SERVER_START,
   EVENT_NOW_PLAYING_COUNT,
+  EVENT_STREAM_RECONNECTED,
 } from '../actions'
 import config from '../config'
 
@@ -16,6 +17,7 @@ const initialState = {
   },
   serverStart: { version: config.version },
   nowPlayingCount: 0,
+  streamReconnected: 0, // Timestamp of last reconnection
 }
 
 export const activityReducer = (previousState = initialState, payload) => {
@@ -44,6 +46,8 @@ export const activityReducer = (previousState = initialState, payload) => {
       }
     case EVENT_NOW_PLAYING_COUNT:
       return { ...previousState, nowPlayingCount: data.count }
+    case EVENT_STREAM_RECONNECTED:
+      return { ...previousState, streamReconnected: Date.now() }
     default:
       return previousState
   }