add env.lat sentinel to hand off formatting from bootstrap to chezmoi

env.lat pads chezmoi download/clone output in gray. When the dotfiles
script starts, it emits ##ENVLAT_END## which tells env.lat's pad() to
switch to pass-through, letting the script use its own formatting.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

run_onchange_after_install_main_deps.sh.tmpl

@@ -17,6 +17,9 @@
 ##   * arch
 
 
+# Signal env.lat to stop padding and let us handle our own formatting
+echo "##ENVLAT_END##"
+
 #Config
 {{ if eq .chezmoi.os "darwin" -}}
 STEPS=9