fix: sync notification peer count with sidebar

[callebtc]

Summary

Fixes a discrepancy between the peer count shown in the sticky notification and the sidebar peer list.

Changes

• Updated PeerManager.getActivePeerIDs() and isPeerActive() to remove the redundant time-based staleness check.
• The notification now relies solely on the peers map state, which is already managed by the periodic cleanupStalePeers job.
• This ensures the notification count matches the sidebar list exactly, as they now use the same source of truth without differing filter logic.