git:last-changed: Fix truncation of colored lines

`cut` counts bytes instead of printable character, making it truncate
colored lines too early.

Fix this by using awk and adding the length difference between a colored
and uncolored version to the allowed length.

COLUMNS is a shell variable and thus needs exporting for `ENVIRON` to
see it in awk.

.config/zsh/autoload/git/git-last-changed

@@ -22,4 +22,9 @@ ls -1p --color="$color_set" "$@" \
 done \
 | sort -r -t$'\t' -k2,2 \
 | column -s$'\t' -t \
-| cut -c -"$COLUMNS"
+| env COLUMNS="$COLUMNS" awk \
+	'{
+		sanit = gensub(/\033\[[0-9;]*m/, "", "g", $0);
+		trunc_len = ENVIRON["COLUMNS"] + length($0) - length(sanit) - 3;
+		print gensub("^(.{" trunc_len "}).{4,}$", "\\1...", "g")
+	}'