fix(functions): stop routing deterministic cd through zoxide's shadow

Verified an agy audit of every bare cd call by hand. conf.d/zoxide.fish
gates alias cd=z behind status is-interactive plus the C1 toggle, and
_zoxide_hook fires on --on-variable PWD, so it tracks a directory
change no matter how PWD got there -- switching to builtin cd loses
zoxide's frecency tracking nothing.

mkcd.fish's single cd and mkrep.fish's 9 (entering the new repo, plus
8 rollback-to-original-directory sites on error paths and --no-cd)
were both intended as exact, deterministic path navigation, never a
zoxide query. The real risk was mkrep's rollback path: if $orig_pwd
ever failed cd's own -d check for any reason, z's fallback branch
queries zoxide for a *guessed* frecent directory instead -- landing a
failed run's cleanup in a directory the caller never asked for, not
the one it was trying to return to. All 9 sites now use builtin cd.

Corrected both functions' CLASSIFICATION from uses-shadow(cd) to
bypasses-shadow(cd) -- neither wanted zoxide's query, they were tagged
that way only because the header audit recorded what the code was
doing at the time, not what it needed.

integrations/fzf.fish's fzf-alt-c-widget also calls bare cd, but it's
vendored upstream code (PatrickF1/fzf.fish) and is itself an
interactive directory-jump binding, not a script/automation caller --
left alone, same as fisher.fish's rm calls.

functions/mkcd.fish

@@ -5,7 +5,7 @@
 #   01-file-and-directory
 #
 # CLASSIFICATION
-#   uses-shadow(cd)
+#   bypasses-shadow(cd)
 #
 # SYNOPSIS
 #   mkcd [-s | --silent] <dir>
@@ -68,7 +68,7 @@ function mkcd --description 'Create a directory (with parents) and cd into it'
         _fish_mkdir_p --tree $dir; or return $status
     end
 
-    cd $dir
+    builtin cd $dir
     or return $status
 
     if test $is_new -eq 1

functions/mkrep.fish

@@ -10,7 +10,7 @@
 #   _mkrep_repo_exists, git
 #
 # CLASSIFICATION
-#   uses-shadow(cd), destructive, network
+#   bypasses-shadow(cd), destructive, network
 #
 # SYNOPSIS
 #   mkrep [--cd | --no-cd] [--mkdir | --no-mkdir] [--git | --no-git]
@@ -307,7 +307,7 @@ function mkrep --description 'Create a directory, cd into it, and git init it'
         _mkrep_say $silent "$c_warn""→$c_reset  $c_arg$dir$c_reset already exists"
     end
 
-    cd $dir
+    builtin cd $dir
     or begin
         echo "$c_err""✘$c_reset  Failed to enter $c_arg$dir$c_reset" >&2
         return 1
@@ -329,7 +329,7 @@ function mkrep --description 'Create a directory, cd into it, and git init it'
         end
         or begin
             echo "$c_err""✘$c_reset  git init failed in $c_arg$dir$c_reset" >&2
-            cd $orig_pwd
+            builtin cd $orig_pwd
             return 1
         end
 
@@ -344,7 +344,7 @@ function mkrep --description 'Create a directory, cd into it, and git init it'
         _mkrep_verbose $silent $verbose "$c_dim""Running: git remote add origin $_flag_remote$c_reset"
         _mkrep_add_origin $silent $_flag_remote
         or begin
-            cd $orig_pwd
+            builtin cd $orig_pwd
             return 1
         end
     end
@@ -354,7 +354,7 @@ function mkrep --description 'Create a directory, cd into it, and git init it'
         test -z "$cmd"; and set cmd $MKREP_REMOTE_CMD
         if test -z "$cmd"
             echo "$c_err""✘$c_reset  --new-remote given no command and \$MKREP_REMOTE_CMD is unset" >&2
-            cd $orig_pwd
+            builtin cd $orig_pwd
             return 1
         end
 
@@ -371,7 +371,7 @@ function mkrep --description 'Create a directory, cd into it, and git init it'
         end
         or begin
             echo "$c_err""✘$c_reset  Remote-create command failed" >&2
-            cd $orig_pwd
+            builtin cd $orig_pwd
             return 1
         end
         _mkrep_say $silent "$c_ok""✔$c_reset  Ran remote-create command"
@@ -393,7 +393,7 @@ function mkrep --description 'Create a directory, cd into it, and git init it'
                 _mkrep_say $silent "$c_warn""→$c_reset  $c_arg$USER/$name$c_reset already exists on $srv_type; linking instead of creating"
                 _mkrep_add_origin $silent $url
                 or begin
-                    cd $orig_pwd
+                    builtin cd $orig_pwd
                     return 1
                 end
             else
@@ -424,7 +424,7 @@ function mkrep --description 'Create a directory, cd into it, and git init it'
                     if string match -q '*{server}*' -- $cmd
                         if test -z "$srv_url"
                             echo "$c_err""✘$c_reset  No base URL resolved for $srv_type (set \$GITEA_URL/\$GITEA_HOST or \$GITLAB_URL/\$GITLAB_HOST)" >&2
-                            cd $orig_pwd
+                            builtin cd $orig_pwd
                             return 1
                         end
                         set cmd (string replace -a '{server}' $srv_url -- $cmd)
@@ -440,7 +440,7 @@ function mkrep --description 'Create a directory, cd into it, and git init it'
                     end
                     or begin
                         echo "$c_err""✘$c_reset  Remote-create command failed" >&2
-                        cd $orig_pwd
+                        builtin cd $orig_pwd
                         return 1
                     end
                     set -l url (_mkrep_remote_url $srv_type $USER $name $srv_url)
@@ -451,7 +451,7 @@ function mkrep --description 'Create a directory, cd into it, and git init it'
     end
 
     if test $do_cd -eq 0
-        cd $orig_pwd
+        builtin cd $orig_pwd
     else
         _mkrep_say $silent "$c_ok""✔$c_reset  Entered $c_arg$dir$c_reset"
     end