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>

test/data/save_repository_booster_test.dart

@@ -34,4 +34,21 @@ void main() {
     expect(repo.boosterCount(BoosterType.shuffle), 0);
     expect(await repo.consumeBooster(BoosterType.shuffle), isFalse);
   });
+
+  test('seedInitialBoosters grants 1 of each once, then is idempotent',
+      () async {
+    final repo = await fresh();
+    await repo.seedInitialBoostersIfNeeded();
+    for (final t in BoosterType.values) {
+      expect(repo.boosterCount(t), 1, reason: t.name);
+    }
+
+    // A second call (and a reload) must not grant again — the flag persists.
+    await repo.seedInitialBoostersIfNeeded();
+    final reloaded = SaveRepository(await SharedPreferences.getInstance());
+    await reloaded.seedInitialBoostersIfNeeded();
+    for (final t in BoosterType.values) {
+      expect(reloaded.boosterCount(t), 1, reason: '${t.name} after reload');
+    }
+  });
 }