feat: create useTransactions hook

- Add useState for transactions array
- Add useEffect to load from AsyncStorage
- Add loading state

hooks/useTransactions.ts

@@ -0,0 +1,34 @@
+import { useState, useEffect } from 'react';
+import AsyncStorage from '@react-native-async-storage/async-storage';
+import { Transaction } from '../types';
+
+const STORAGE_KEY = '@finance_transactions';
+
+export const useTransactions = () => {
+  const [transactions, setTransactions] = useState<Transaction[]>([]);
+  const [loading, setLoading] = useState(true);
+
+  const loadTransactions = async () => {
+    try {
+      setLoading(true);
+      const stored = await AsyncStorage.getItem(STORAGE_KEY);
+      if (stored) {
+        setTransactions(JSON.parse(stored));
+      }
+    } catch (error) {
+      console.error('Error loading transactions:', error);
+    } finally {
+      setLoading(false);
+    }
+  };
+
+  useEffect(() => {
+    loadTransactions();
+  }, []);
+
+  return {
+    transactions,
+    loading,
+    refresh: loadTransactions,
+  };
+};