feat(dashboard): lazy routes, Needs-you strip, URL state, exact numbers

- Workspace, SettingsHub, SessionDetail and the Workflow sub-tab are lazy
  (main bundle 2,166 kB -> ~920 kB), wrapped in RouteErrorBoundary: a stale
  chunk after a self-update reloads once (vite:preloadError too), any other
  error shows a Reload panel instead of a blank page.
- Live refresh: lib/throttle.ts + hooks/useLiveRefresh.ts replace trailing
  debounces that froze under a steady event stream; refresh skips hidden
  tabs and refetches after a WebSocket reconnect. Monitor loads only while
  shown, with one batched GET /api/agents?session_ids= instead of N+1; a
  failing endpoint is an inline error, not a blank Dashboard.
- NeedsYouStrip on Monitor and above Analytics. Tabs, filters, page, sort
  and search live in the URL (Dashboard, Sessions, Activity, SessionDetail).
- Sessions: tool / workspace / date-range filters, CSV/JSON export
  (formula-neutralised), focusable row links, Open in workspace (the dead
  /run links are gone), stale responses dropped, error + Retry.
- Fixes: "NaNs" durations, 30/7-day charts skipping idle days, weekday
  labels west of UTC (now averages), cache hit rate denominator, billable
  tokens vs cache reads, exact tool-call counts, "To" date = end of day,
  invalid ?from= no longer throws, recent list no longer shrinks to 15,
  stable message keys, transcript switch races.
- Light-theme-unreadable bg-black code panels and dark-only DAG fills use
  tokens; status configs and chart colours use theme tokens; Health tab
  and other literals translated.
- Server (additive): GET /api/agents?session_ids=, GET /api/sessions
  awaiting=1&from=&to=, stats tool_call_count/distinct_tool_count, event
  rows carry session/agent labels.

client/src/components/StatusBadge.tsx

@@ -79,8 +79,8 @@ export const REASON_ICONS: Record<AwaitingReason, LucideIcon> = {
 /**
  * The "why" chip nested inside a Waiting badge: a small rounded pill with the
  * reason's icon and short label. Urgent reasons (permission prompts,
- * interruptions) get a hotter amber fill than the calm idle-between-turns
- * ones so a scan of a list surfaces the rows that actually block on the human.
+ * interruptions) get the amber warning fill; the calm idle-between-turns
+ * ones stay neutral, so a scan of a list surfaces the rows that actually block on the human.
  */
 function ReasonChip({ reason }: { reason: AwaitingReason }) {
   const { t } = useTranslation();
@@ -91,7 +91,7 @@ function ReasonChip({ reason }: { reason: AwaitingReason }) {
       className={`inline-flex items-center gap-1 rounded-full border px-1.5 text-[10px] font-medium leading-4 ${
         cfg.urgent
           ? "bg-status-warning/15 border-status-warning/25 text-status-warning"
-          : "bg-yellow-500/10 border-yellow-500/20 text-yellow-700/90 dark:text-yellow-400/90"
+          : "bg-surface-3 border-border text-fg-secondary"
       }`}
     >
       <Icon className="w-2.5 h-2.5 flex-shrink-0" aria-hidden="true" />