In-game commands to send tc / items will never happen. There are various reasons for that with main one being the fact that it essentially implies having two completely separate trading systems - one web based, written in PHP, and another as part of the game server, written in C++. Maintaining these two separate systems would be a nightmare as they'd always have their own unique issues and would still need to be kept in sync whenever there are changes done to either.

Trading from modern game UI might become a thing in future. There are certain security concerns in terms of preventing fraud done by third party lua scripts, but they're generally resolvable to a point where we'd be confident users cannot get scammed unless they go out of their way to break their own game client.