UI polish across sections: one server selector, skeletons, inline errors

- Every section puts the hub's server selector in the chrome slot, the
  same place and gap as the Dashboard.
- Data regions load with a Skeleton and fail inline with Retry; KPIs show
  the no-data dash instead of 0 when a server did not answer. Settings
  keeps its header and selector while loading or failing.
- Cache, Apps and Logs headers group secondary or hub-refused actions in
  menus; app descriptions clamp to two lines; Unknown cells say why.
- DNS Client: Protocol label, Resolve and Import together. DHCP and Query
  Logs empty states with actions. View Logs list capped with scroll.
- Blocking: Lists KPI tiles like the Overview, app list table fits its
  panel with one-line URLs. Status re-reads on tab return at most once
  a minute.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

hub/merge.ts

@@ -162,6 +162,16 @@ export function mergeTopResponses(
   return { topDomains: [] }
 }
 
+/* A counter as a number: a number, or a numeric string some servers send. Anything else is not a counter. */
+function counter(value: unknown): number | null {
+  if (typeof value === 'number') return Number.isFinite(value) ? value : null
+  if (typeof value === 'string' && value.trim() !== '' && Number.isFinite(Number(value))) return Number(value)
+  return null
+}
+
+/* What a server holds, as the "Server" panel of the Dashboard counts it. */
+const HELD = ['zones', 'cachedEntries', 'allowedZones', 'blockedZones', 'allowListZones', 'blockListZones']
+
 /*
 `dashboard/stats/get`. Every numeric counter in `stats` is summed. That includes
 `totalClients` (distinct clients), which over-counts a client seen by both servers:
@@ -174,9 +184,14 @@ export function mergeStats(responses: DashboardStats[]): DashboardStats {
   const stats: Record<string, number> = {}
   for (const r of responses) {
     for (const [key, value] of Object.entries(r.stats ?? {})) {
-      if (typeof value === 'number') stats[key] = (stats[key] ?? 0) + value
+      const n = counter(value)
+      if (n !== null) stats[key] = (stats[key] ?? 0) + n
     }
   }
+  /* The Dashboard's "Server" panel counts what each server holds (zones, cache, allow and block
+     lists). Those are sums too, and a server that left one out counts as none, so the field is
+     never missing from the total. */
+  for (const key of HELD) stats[key] ??= 0
 
   const merged: DashboardStats = { ...first, stats }
   const main = mergeChart(responses.map((r) => r.mainChartData), true)