Chat: Add setting to control space after autocomplete

[SmallJoker]

Requested here https://irc.luanti.org/luanti-dev/2026-07-25#i_6333876

• set to true (default)
  • "hello singleplayer "
  • "singleplayer: "
• set to false
  • "hello singleplayer" (no tailing space)
  • "singleplayer: " (no change)

Useful to add punctuation after the player name. I am however used to have a space character inserted after autocomplete, thus introduced new setting.

To do

This PR is Ready for Review.

How to test

1. Join a world (or use the ncurses terminal)
2. Autocomplete
3. Compare
4. ???
5. Profit

[Zughy]

Can't we just have the no-space option? If people want a space after like if it was a terminal autocomplete, they can just press space. I don't think a setting is needed

[SmallJoker]

I would like to have the space character.

1. It gives a visual feedback that the autocompletion is done.
2. It's convenient for entering chat commands and other applications handle it the same way:
   • HexChat
   • GitHub (@ Name)
   • Outlook (@ Name)

[sfan5]

how about allowing an arbitrary string? My IRC client completes : and I could imagine some people might want , .

[SmallJoker]

how about allowing an arbitrary string?

Space and empty string are not something that can be distinguished without hacks. The hack I implemented for this request requires surrounding the string with non-space characters.
Please feel free to provide better ideas.