feat(db): Force save on mission end

This commit introduces a mission event handler that forces a database save with backup when the mission ends.

Key changes:

*   **`XEH_preInit_server.sqf`:** Added an "Ended" mission event handler that calls the `ArmaDragonflyClient` extension with the "savedb" command and logs an info message. This ensures that the database is saved when the mission ends, providing a backup in case of unexpected server shutdowns.

addons/db/XEH_preInit_server.sqf

@@ -1 +1,6 @@
 #include "script_component.hpp"
+
+addMissionEventHandler ["Ended", {
+    "ArmaDragonflyClient" callExtension ["savedb", []];
+    INFO("Mission ended - forced save with backup");
+}];