A focused hotfix for save files.

FIXED
- Save/load now preserves your country's history. Diplomacy, political, and war logs were being dropped on save and reset when you loaded — so the National Log and Government Performance reports lost their record each time. They now persist correctly.
- Pending decisions now survive a save. A called snap election and an awaiting occupation (annex/withdraw) decision were being lost on load; both are now kept.
- Added an automated save round-trip check so this class of issue can't slip through again.

Note: this repairs saves going forward — history already lost in an earlier save can't be recovered, but from this build on everything persists correctly.

Thanks again to everyone reporting issues — keep them coming.