feat: trakt integration

close #617

lib/services/trakt/trakt_account_store.dart

@@ -0,0 +1,37 @@
+import 'package:shared_preferences/shared_preferences.dart';
+
+import 'trakt_constants.dart';
+import 'trakt_session.dart';
+
+/// Per-Plex-profile persistence of Trakt OAuth sessions.
+///
+/// Each Plex Home user can link a different Trakt account. Pass an empty
+/// `userUuid` to fall back to a single global slot (used before the user has
+/// selected a profile).
+class TraktAccountStore {
+  static const String _baseKey = 'trakt_session';
+
+  TraktAccountStore._();
+  static final TraktAccountStore instance = TraktAccountStore._();
+
+  Future<TraktSession?> load(String userUuid) async {
+    final prefs = await SharedPreferences.getInstance();
+    final raw = prefs.getString(traktUserKey(userUuid, _baseKey));
+    if (raw == null) return null;
+    try {
+      return TraktSession.decode(raw);
+    } catch (_) {
+      return null;
+    }
+  }
+
+  Future<void> save(String userUuid, TraktSession session) async {
+    final prefs = await SharedPreferences.getInstance();
+    await prefs.setString(traktUserKey(userUuid, _baseKey), session.encode());
+  }
+
+  Future<void> clear(String userUuid) async {
+    final prefs = await SharedPreferences.getInstance();
+    await prefs.remove(traktUserKey(userUuid, _baseKey));
+  }
+}