重构项目结构，删除未使用的组件和文件，添加主页和模态页实现

features/system/screens/modal-screen.tsx

@@ -0,0 +1,38 @@
+import { Link } from "expo-router";
+import { StyleSheet, Text, View } from "react-native";
+
+export function ModalScreen() {
+  return (
+    <View style={styles.container}>
+      <Text style={styles.title}>Modal Route</Text>
+      <Text style={styles.subtitle}>This screen is presented with modal behavior on native.</Text>
+      <Link href="/" dismissTo style={styles.link}>
+        Back to home
+      </Link>
+    </View>
+  );
+}
+
+const styles = StyleSheet.create({
+  container: {
+    flex: 1,
+    alignItems: "center",
+    justifyContent: "center",
+    padding: 20,
+    gap: 8,
+  },
+  title: {
+    fontSize: 24,
+    fontWeight: "700",
+  },
+  subtitle: {
+    fontSize: 14,
+    color: "#5c6169",
+    textAlign: "center",
+  },
+  link: {
+    marginTop: 8,
+    fontSize: 16,
+    fontWeight: "600",
+  },
+});