feat(app): add manual entry and sharing flows

lib/core/services/permission_service.dart

@@ -0,0 +1,31 @@
+import 'dart:io';
+
+import 'package:permission_handler/permission_handler.dart';
+
+/// 공용 권한 유틸리티
+class PermissionService {
+  static Future<bool> checkAndRequestBluetoothPermission() async {
+    if (!Platform.isAndroid && !Platform.isIOS) {
+      return true;
+    }
+
+    final permissions = <Permission>[
+      Permission.bluetooth,
+      Permission.bluetoothScan,
+      Permission.bluetoothConnect,
+      Permission.bluetoothAdvertise,
+    ];
+
+    for (final permission in permissions) {
+      final status = await permission.status;
+      if (status.isGranted) {
+        continue;
+      }
+      final result = await permission.request();
+      if (!result.isGranted) {
+        return false;
+      }
+    }
+    return true;
+  }
+}