Implement persistent hardcore death bans (XUID + IP) for dedicated server

On the dedicated server, hardcore death now persists XUID and IP bans to
banned-players.json and banned-ips.json via the Access system, and
disconnects the player. Bans survive server restarts. Client-hosted games
retain the existing in-memory XUID ban with force-save behavior.

- Add hardcore property to server.properties (forces Hard difficulty)
- Add LevelData::setHardcore() so loaded worlds respect the server config
- Add PlayerList::banPlayerForHardcoreDeath() with persistent XUID + IP bans
- Reject respawn requests server-side in hardcore mode
- Ensure server-side player ticks run without move packets (fixes
  environmental damage not applying for some clients)
- Restore 0x8 hardcore bit on LoginPacket/RespawnPacket wire format so
  the client-side death screen detects hardcore mode correctly

Minecraft.Client/MinecraftServer.cpp

@@ -1007,6 +1007,9 @@ bool MinecraftServer::loadLevel(LevelStorageSource *storageSource, const wstring
 #endif
 		levels[i]->getLevelData()->setGameType(gameType);
 
+		// Apply hardcore flag from host option to level data so loaded worlds respect server.properties
+		levels[i]->getLevelData()->setHardcore(isHardcore());
+
 		if(app.getLevelGenerationOptions() != nullptr)
 		{
 			LevelGenerationOptions *mapOptions = app.getLevelGenerationOptions();