fix(ui): сохранить данные дашборда при сбоях и гонках запросов

lib/dashboard-source-state.ts

@@ -0,0 +1,12 @@
+export const DASHBOARD_SOURCES = {
+  servers: "Серверы", probes: "Пробы", bgp: "BGP", gre: "GRE",
+  wg: "WireGuard", vxlan: "VXLAN", traffic: "Трафик",
+  internetPath: "Internet path", events: "События",
+} as const
+
+export type DashboardSource = keyof typeof DASHBOARD_SOURCES
+export type DashboardSources = Partial<Record<DashboardSource, { receivedAt: number | null; error: string | null; sampledAt?: string }>>
+
+export function updateDashboardSource(previous: DashboardSources, source: DashboardSource, error: string | null, now: number, sampledAt?: string): DashboardSources {
+  return { ...previous, [source]: { receivedAt: error ? previous[source]?.receivedAt ?? null : now, error, sampledAt: error ? previous[source]?.sampledAt : sampledAt } }
+}