bat + yazi flavors: sync configs, external the purescript syntax clone

- dot_config/bat: config + cyberdream theme synced; embedded
  sublime-purescript-syntax git clone (with dot_git) replaced by a
  git-repo external (clone-when-missing, ff-only)
- run_onchange bat cache --build hook keyed on theme/config
- yazi cyberdream flavor synced; flavors un-ignored in .chezmoiignore

run_onchange_after_build-bat-cache.sh.tmpl

@@ -0,0 +1,7 @@
+#!/bin/sh
+# Rebuild bat's syntax/theme cache when managed inputs change.
+# themes hash: {{ include "dot_config/bat/themes/cyberdream.tmTheme" | sha256sum }}
+# config hash: {{ include "dot_config/bat/config" | sha256sum }}
+set -eu
+command -v bat >/dev/null 2>&1 || exit 0
+bat cache --build >/dev/null