feat: secure home credentials

lib/services/credentials_storage.dart

@@ -0,0 +1,28 @@
+import 'package:flutter_secure_storage/flutter_secure_storage.dart';
+
+abstract class CredentialsStorage {
+  Future<String?> getApiKey(String homeId);
+
+  Future<void> setApiKey(String homeId, String apiKey);
+
+  Future<void> deleteApiKey(String homeId);
+}
+
+class SecureCredentialsStorage implements CredentialsStorage {
+  static const _storage = FlutterSecureStorage();
+
+  static String _apiKeyStorageKey(String homeId) =>
+      'ignis_home_api_key_$homeId';
+
+  @override
+  Future<String?> getApiKey(String homeId) =>
+      _storage.read(key: _apiKeyStorageKey(homeId));
+
+  @override
+  Future<void> setApiKey(String homeId, String apiKey) =>
+      _storage.write(key: _apiKeyStorageKey(homeId), value: apiKey);
+
+  @override
+  Future<void> deleteApiKey(String homeId) =>
+      _storage.delete(key: _apiKeyStorageKey(homeId));
+}