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/__tests__/StatusBadge.test.tsx

@@ -64,7 +64,7 @@ describe("AgentStatusBadge", () => {
     expect(screen.getByText("Waiting")).toBeInTheDocument();
     const dot = container.querySelector(".animate-pulse-dot");
     expect(dot).toBeInTheDocument();
-    expect(container.querySelector(".bg-yellow-400")).toBeInTheDocument();
+    expect(container.querySelector(".bg-status-warning")).toBeInTheDocument();
   });
 });
 
@@ -94,7 +94,7 @@ describe("SessionStatusBadge", () => {
     expect(screen.getByText("Waiting")).toBeInTheDocument();
     const dot = container.querySelector(".animate-pulse-dot");
     expect(dot).toBeInTheDocument();
-    expect(container.querySelector(".bg-yellow-400")).toBeInTheDocument();
+    expect(container.querySelector(".bg-status-warning")).toBeInTheDocument();
   });
 });
 
@@ -135,10 +135,14 @@ describe("awaiting-reason suffix", () => {
   });
 
   it("marks urgent reasons with the hotter amber tint", () => {
-    const { container } = render(<AgentStatusBadge status="waiting" reason="notification" />);
-    expect(container.querySelector(".text-status-warning")).toBeInTheDocument();
-    const { container: calm } = render(<AgentStatusBadge status="waiting" reason="stop" />);
-    expect(calm.querySelector(".text-status-warning")).not.toBeInTheDocument();
+    render(<AgentStatusBadge status="waiting" reason="notification" />);
+    expect(screen.getByText("Needs input").closest("span.rounded-full")).toHaveClass(
+      "text-status-warning"
+    );
+    render(<AgentStatusBadge status="waiting" reason="stop" />);
+    expect(screen.getByText("Turn done").closest("span.rounded-full")).not.toHaveClass(
+      "text-status-warning"
+    );
   });
 
   it("compact mode suppresses the inline chip but keeps the hover tooltip", () => {