fix(player): restore missing additional save timer and reduce autosave interval

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>

src/server/game/Entities/Player/PlayerUpdates.cpp

@@ -332,6 +332,28 @@ void Player::Update(uint32 p_time)
         }
     }
 
+    if (m_additionalSaveTimer)
+    {
+        if (p_time >= m_additionalSaveTimer)
+        {
+            m_additionalSaveTimer = 0;
+            CharacterDatabaseTransaction trans = CharacterDatabase.BeginTransaction();
+
+            if (m_additionalSaveMask & ADDITIONAL_SAVING_INVENTORY_AND_GOLD)
+                SaveInventoryAndGoldToDB(trans);
+
+            if (m_additionalSaveMask & ADDITIONAL_SAVING_QUEST_STATUS)
+                _SaveQuestStatus(trans);
+
+            CharacterDatabase.CommitTransaction(trans);
+            m_additionalSaveMask = 0;
+        }
+        else
+        {
+            m_additionalSaveTimer -= p_time;
+        }
+    }
+
     // Handle Water/drowning
     HandleDrowning(p_time);