feat: analytics parity — tool cost, date ranges, budgets, query explorer, replay, snapshots (v2.4.0)

Analytics parity phases 2–7 (docs/plans/analytics-parity/), built on
138e706 and ported onto v2.3.1:
- Cost by AI tool (?tool= on cost/analytics/stats/workflows, by_tool,
  Codex fast/priority and flex tiers, agenthub_cost_usd_total{tool,model})
- Date ranges (from/to) on cost/analytics/workflows; Analytics range select
  with Today / This week (Monday) / This month (1st) / 7d / 30d / 90d / All /
  Custom; workflow filters carried into workflow-stats.js (read worker)
- Budgets and cost alerts as alert rule types (alert_rules rebuilt without
  its rule_type CHECK), GET /api/budgets/status, rule preview, spend pace,
  status-bar budget chip; rules stay editable in place
- Query Explorer (/query, allowlisted sort, CSV/JSON export) and scheduled
  reports (report_definitions/report_runs, Settings → Reports)
- Session Replay tab and immutable snapshots (session_snapshots, /snapshot/:token)
- Remote Codex sync, push ingest with a hashed token, privacy redaction and
  ignored folders (Settings → Data), Cursor sessions (no cost)
- Read-only MCP server, statusline, Grafana/Prometheus files

Also: resizable sidebar, pet run/wave animations, the workspace home keeps a
half-typed prompt, and the pre-commit hook runs only the related tests for a
small commit.

client/src/components/SessionOverview.tsx

@@ -76,6 +76,8 @@ import type { Agent, Session, SessionStats } from "../lib/types";
 interface SessionOverviewProps {
   session: Session;
   agents: Agent[];
+  /** Frozen stats (a session snapshot): shown as given, never fetched or refreshed. */
+  stats?: SessionStats;
 }
 
 /** Throttle window for stats refresh - coalesces bursts of hook events into one fetch. */
@@ -160,18 +162,19 @@ function ToolUsageRow({ toolName, count, max }: { toolName: string; count: numbe
   );
 }
 
-export function SessionOverview({ session, agents }: SessionOverviewProps) {
+export function SessionOverview({ session, agents, stats: frozen }: SessionOverviewProps) {
   const { t } = useTranslation("sessions");
-  const [stats, setStats] = useState<SessionStats | null>(null);
+  const [fetched, setStats] = useState<SessionStats | null>(null);
+  const stats = frozen ?? fetched;
   const fetchingRef = useRef(false);
 
   // Tick clock every 30s so a still-active session's "duration" tile stays current.
   const [now, setNow] = useState(() => Date.now());
   useEffect(() => {
-    if (session.status !== "active") return;
+    if (frozen || session.status !== "active") return;
     const id = window.setInterval(() => setNow(Date.now()), 30_000);
     return () => window.clearInterval(id);
-  }, [session.status]);
+  }, [frozen, session.status]);
 
   // A refresh asked for while one is in flight is not dropped: it runs once
   // when the current one settles (that is the throttle's trailing call).
@@ -198,6 +201,7 @@ export function SessionOverview({ session, agents }: SessionOverviewProps) {
 
   // Initial load + reload when the session id changes.
   useEffect(() => {
+    if (frozen) return;
     fetchStats();
     // eslint-disable-next-line react-hooks/exhaustive-deps
   }, [session.id]);
@@ -206,6 +210,7 @@ export function SessionOverview({ session, agents }: SessionOverviewProps) {
   // stream still refreshes) and again after a reconnect.
   useLiveRefresh(() => void fetchStats(), {
     throttleMs: REFRESH_THROTTLE_MS,
+    enabled: !frozen,
     match: (msg) => {
       if (isRemoteDataRefreshMessage(msg)) return true;
       if (