[FEATURE] move hist envs to shell config for consistancy

[richen604]

Makes sense to add the below in shell.nix instead

Discussed in #152

^{Originally posted by Roverp1 September 20, 2025}
Hi! I wanted to ask question about source code.
I've noticed you configure history (with this weird setopt syntax) in home.sessionVariables. I'm curious why was it chosen over configuring history in shell.nix?
Does it make this configuration shell agnostic 🤔

       # History configuration // explicit to not nuke history
      HISTFILE = "\${HISTFILE:-\$HOME/.zsh_history}";
      HISTSIZE = "10000";
      SAVEHIST = "10000";
      setopt_EXTENDED_HISTORY = "true";
      setopt_INC_APPEND_HISTORY = "true";
      setopt_SHARE_HISTORY = "true";
      setopt_HIST_EXPIRE_DUPS_FIRST = "true";
      setopt_HIST_IGNORE_DUPS = "true";
      setopt_HIST_IGNORE_ALL_DUPS = "true";

code from xdg.nix