refactor: use __fish_palette in small utility functions (2/2)

25 duplicated declarations replaced by 7 calls. Completes the 33 structural
conversions: 167 declarations removed, 33 calls added, and --structural
confirms every one of the 33 diffs is declaration removals plus inserted
calls only -- no rendering text touched.

functions/y.fish is the one file in the repo with no trailing newline on
main; its original file ending is preserved rather than normalised.

functions/replay.fish

@@ -27,11 +27,7 @@ function replay --description 'Run Bash commands replaying changes in Fish'
         case -v --version
             echo "replay, version 1.2.1"
         case "" -h --help
-            set -l c_head (set_color --bold cyan)
-            set -l c_cmd (set_color --bold)
-            set -l c_flag (set_color yellow)
-            set -l c_arg (set_color cyan)
-            set -l c_reset (set_color normal)
+            __fish_palette
             echo "$c_head""Usage:$c_reset $c_cmd""replay$c_reset $c_arg""<commands>$c_reset  Run Bash commands replaying changes in Fish"
             echo "$c_head""Options:$c_reset"
             echo "       $c_flag-v$c_reset or $c_flag--version$c_reset  Print version"