tray: selectable exit nodes + push-based network list refresh

Make the tray Exit Node submenu selectable (mutually exclusive, sourced from
ListNetworks by NetID) instead of read-only.

Add networksRevision to the status snapshot, bumped by the route manager on
network-map and selection changes, so the tray and the React NetworksContext
re-fetch ListNetworks via the push stream instead of polling. The peer-status
route list only carries chosen routes, so a candidate exit node appearing or
disappearing would otherwise never reach the UI.

client/ui/i18n/locales/de/common.json

@@ -38,6 +38,7 @@
     "notify.error.connect": "Verbindung fehlgeschlagen",
     "notify.error.disconnect": "Trennen fehlgeschlagen",
     "notify.error.switchProfile": "Wechsel zu {profile} fehlgeschlagen",
+    "notify.error.exitNode": "Exit-Node {name} konnte nicht aktualisiert werden",
     "notify.sessionExpired.title": "NetBird-Sitzung abgelaufen",
     "notify.sessionExpired.body": "Ihre NetBird-Sitzung ist abgelaufen. Bitte melden Sie sich erneut an.",
     "notify.sessionWarning.title": "Sitzung läuft bald ab",

client/ui/i18n/locales/en/common.json

@@ -38,6 +38,7 @@
     "notify.error.connect": "Failed to connect",
     "notify.error.disconnect": "Failed to disconnect",
     "notify.error.switchProfile": "Failed to switch to {profile}",
+    "notify.error.exitNode": "Failed to update exit node {name}",
     "notify.sessionExpired.title": "NetBird session expired",
     "notify.sessionExpired.body": "Your NetBird session has expired. Please log in again.",
     "notify.sessionWarning.title": "Session expires soon",

client/ui/i18n/locales/hu/common.json

@@ -38,6 +38,7 @@
     "notify.error.connect": "Csatlakozás sikertelen",
     "notify.error.disconnect": "Bontás sikertelen",
     "notify.error.switchProfile": "Átváltás sikertelen erre: {profile}",
+    "notify.error.exitNode": "A kilépő csomópont frissítése sikertelen: {name}",
     "notify.sessionExpired.title": "NetBird munkamenet lejárt",
     "notify.sessionExpired.body": "A NetBird munkamenet lejárt. Kérjük, jelentkezzen be újra.",
     "notify.sessionWarning.title": "Munkamenet hamarosan lejár",