The m_additionalSaveTimer was never processed in the update loop, so quick
partial saves after important events (rare+ item pickups, quest completions)
never fired. This caused players to lose progress on disconnect/crash since
only the 15-minute full autosave protected them.
- Add m_additionalSaveTimer tick logic to Player::Update
- Reduce default PlayerSaveInterval from 900000 (15 min) to 300000 (5 min)
Co-authored-by: Cursor <cursoragent@cursor.com>