feat(stats): add v1 immersion stats dashboard (#19)

stats/src/hooks/useOverview.ts

@@ -0,0 +1,36 @@
+import { useState, useEffect } from 'react';
+import { getStatsClient } from './useStatsApi';
+import type { OverviewData, SessionSummary } from '../types/stats';
+
+export function useOverview() {
+  const [data, setData] = useState<OverviewData | null>(null);
+  const [sessions, setSessions] = useState<SessionSummary[]>([]);
+  const [loading, setLoading] = useState(true);
+  const [error, setError] = useState<string | null>(null);
+
+  useEffect(() => {
+    let cancelled = false;
+    setLoading(true);
+    setError(null);
+    const client = getStatsClient();
+    Promise.all([client.getOverview(), client.getSessions(50)])
+      .then(([overview, allSessions]) => {
+        if (cancelled) return;
+        setData(overview);
+        setSessions(allSessions);
+      })
+      .catch((err) => {
+        if (cancelled) return;
+        setError(err instanceof Error ? err.message : String(err));
+      })
+      .finally(() => {
+        if (cancelled) return;
+        setLoading(false);
+      });
+    return () => {
+      cancelled = true;
+    };
+  }, []);
+
+  return { data, sessions, setSessions, loading, error };
+}