feat: Add new substitutes for guix and set right guix path

home/modules/programs/fish.nix

@@ -43,6 +43,9 @@ in
         };
         shellInitLast = # fish
           ''
+            if test -e ~/.config/guix/current/bin/guix
+              fish_add_path -pPm ~/.config/guix/current/bin
+            end
             if test -d ~/.guix-profile
               set -gx GUIX_PROFILE ~/.guix-profile
               if test -f $GUIX_PROFILE/etc/profile

nixos/modules/programs/guix.nix

@@ -1,6 +1,7 @@
 {
   lib,
   config,
+  options,
   ...
 }:
 let
@@ -19,6 +20,10 @@ in
         enable = true;
         dates = "weekly";
       };
+      substituters.urls = [
+        "https://mirror.sjtu.edu.cn/guix/"
+      ]
+      ++ options.services.guix.substituters.urls.default;
     };
   };
 }