feat(help): standardize colored --help output across functions

Add the established c_head/c_cmd/c_flag/c_dim/c_arg color scheme to
--help (or usage-on-error) output in play-media and 13 other functions
that lacked it or used an ad hoc scheme: bkg, detach, replay, p, y,
spark, wake-lock, open-url, repo-open, dng2avif, dockup, fish-deps
(__fish_deps_help), and scrub.

Also tweak the standard itself:
- c_cmd now uses plain `set_color --bold` instead of `--bold white`,
  so the command name adapts to the terminal's foreground instead of
  forcing white text that washes out on light-background themes.
  Applied across all functions already using the pattern.
- jobrunner's reset variable renamed from c_rst to c_reset to match
  the naming used everywhere else.

functions/replay.fish

@@ -27,10 +27,15 @@ function replay --description 'Run Bash commands replaying changes in Fish'
         case -v --version
             echo "replay, version 1.2.1"
         case "" -h --help
-            echo "Usage: replay <commands>  Run Bash commands replaying changes in Fish"
-            echo "Options:"
-            echo "       -v or --version  Print version"
-            echo "       -h or --help     Print this help message"
+            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)
+            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"
+            echo "       $c_flag-h$c_reset or $c_flag--help$c_reset     Print this help message"
         case \*
             set --local env
             set --local sep @$fish_pid(random)(command date +%s)