fix(boosters): address final-review findings

- daily claim: record the claim before granting boosters, so a crash
  mid-claim forfeits at most one reward instead of allowing a re-claim
  (booster farming) on next launch.
- game screen: disarm the booster target synchronously before awaiting,
  so a rapid second board tap can't double-fire a use or stack a dialog.
- new players: seed one of each booster once (idempotent persisted flag),
  fulfilling the spec's starting inventory. Wired in main().

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

lib/main.dart

@@ -28,6 +28,8 @@ const contentBaseUrl = String.fromEnvironment(
 Future<void> main() async {
   WidgetsFlutterBinding.ensureInitialized();
   final saveRepository = await SaveRepository.open();
+  // New players start with one of each booster (idempotent after the first run).
+  await saveRepository.seedInitialBoostersIfNeeded();
 
   // Analytics: real GA4 traffic flows only from release builds so development
   // never pollutes production. If Firebase init fails (e.g. missing native