feat: add rofi-project-opener for rofi-based project launching

Adds package and HM module for quickly opening projects in terminals.
Uses XDG config file instead of environment variables for better
shell-independence and proper NixOS PATH sourcing.

pkgs/default.nix

@@ -7,6 +7,7 @@
   mem0 = pkgs.callPackage ./mem0 {};
   msty-studio = pkgs.callPackage ./msty-studio {};
   pomodoro-timer = pkgs.callPackage ./pomodoro-timer {};
+  rofi-project-opener = pkgs.callPackage ./rofi-project-opener {};
   stt-ptt = pkgs.callPackage ./stt-ptt {};
   tuxedo-backlight = pkgs.callPackage ./tuxedo-backlight {};
   zellij-ps = pkgs.callPackage ./zellij-ps {};