winWithMetadata method
ENH-96: same transition as win, plus metadata recorded on the
terminal GameSessionTimelineEntry after sanitization (see
_sanitizeMetadata's doc) — win itself just delegates here with an
empty map, so its own behavior/signature is 100% unchanged.
Implementation
SdkResult<GameSessionSnapshot> winWithMetadata(
Map<String, Object?> metadata,
) => _transition(
GameSessionPhase.won,
from: {GameSessionPhase.playing},
metadata: metadata,
);