neomutt: Rename render-prettyhtml to neomutt-renderhtml

Also ensure the temporary file

a) is always different, by using mktemp
and b) is always deleted with an EXIT trap

office/.local/bin/neomutt-renderhtml

@@ -2,7 +2,11 @@
 # render html as markdown and display in glow, supports syntax highlighting
 # requires: html2text, glow or bat
 # author: CEUK
-fpath=/tmp/mutt.md
+
+fpath=$(mktemp --suffix=-neomutt-render.html)
+
+#shellcheck disable=SC2064 # we want to expand it instantly
+trap "rm -f -- ${fpath@Q}" EXIT
 
 perl -0777pe 's/(<code class="sourceCode\s?)(\w+?)(">)(.*?)(<\/code>)/\1\2\3\n```\2\n\4\n```\n\5/gs' "$1" | html2text | sed -re 's/^\s+(```(\w+)?)/\1/gm' -e 's/\x1b\[[6-9;]*m//g' >"$fpath"
 
@@ -13,5 +17,3 @@ elif command -v glow >/dev/null 2>&1; then
 else
     sed 's/\x1b\[[6-9;]*m//g' <"$fpath"
 fi
-
-rm "$fpath" || exit 1