feat: add useSettings hook for admin price management

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/admin/settings/useSettings.js

@@ -0,0 +1,46 @@
+import { useState, useEffect, useCallback } from 'react';
+import { supabase } from '../../lib/supabase';
+
+export function useSettings() {
+  const [prices, setPrices] = useState({ 200: 2000, 300: 3000 });
+  const [loading, setLoading] = useState(true);
+  const [error, setError] = useState(null);
+
+  const fetchPrices = useCallback(async () => {
+    const { data, error } = await supabase
+      .from('settings')
+      .select('key, value')
+      .in('key', ['price_200', 'price_300']);
+
+    if (error) {
+      setError(error.message);
+    } else if (data) {
+      const map = {};
+      data.forEach(({ key, value }) => {
+        const thickness = parseInt(key.replace('price_', ''), 10);
+        map[thickness] = Number(value);
+      });
+      setPrices((prev) => ({ ...prev, ...map }));
+    }
+    setLoading(false);
+  }, []);
+
+  useEffect(() => {
+    fetchPrices();
+  }, [fetchPrices]);
+
+  const updatePrice = async (key, value) => {
+    const { error } = await supabase
+      .from('settings')
+      .update({ value: String(value), updated_at: new Date().toISOString() })
+      .eq('key', key);
+
+    if (!error) {
+      const thickness = parseInt(key.replace('price_', ''), 10);
+      setPrices((prev) => ({ ...prev, [thickness]: Number(value) }));
+    }
+    return { error };
+  };
+
+  return { prices, loading, error, updatePrice };
+}