zsh: fix trailing slash breaking zshenv

A trailing slash in user.users.<user>.home broke zshenv setup in Home
Manager. The generated ~/.zshenv ended up sourcing itself, causing an
infinite loop at shell startup.

Author: landon-buttars-wgu

modules/programs/zsh/lib.nix

@@ -3,7 +3,7 @@ let
   cfg = config.programs.zsh;
 in
 rec {
-  homeDir = config.home.homeDirectory;
+  homeDir = cleanPathStr config.home.homeDirectory;
 
   /*
     Escape a path string for shell usage and remove trailing slashes.