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

stats/src/hooks/useTrends.ts

@@ -0,0 +1,37 @@
+import { useState, useEffect } from 'react';
+import { getStatsClient } from './useStatsApi';
+import type { TrendsDashboardData } from '../types/stats';
+
+export type TimeRange = '7d' | '30d' | '90d' | 'all';
+export type GroupBy = 'day' | 'month';
+
+export function useTrends(range: TimeRange, groupBy: GroupBy) {
+  const [data, setData] = useState<TrendsDashboardData | null>(null);
+  const [loading, setLoading] = useState(true);
+  const [error, setError] = useState<string | null>(null);
+
+  useEffect(() => {
+    let cancelled = false;
+    setLoading(true);
+    setError(null);
+    getStatsClient()
+      .getTrendsDashboard(range, groupBy)
+      .then((nextData) => {
+        if (cancelled) return;
+        setData(nextData);
+      })
+      .catch((err) => {
+        if (cancelled) return;
+        setError(err instanceof Error ? err.message : String(err));
+      })
+      .finally(() => {
+        if (cancelled) return;
+        setLoading(false);
+      });
+    return () => {
+      cancelled = true;
+    };
+  }, [range, groupBy]);
+
+  return { data, loading, error };
+}