runtime(lf): use syn iskeyword in syntax script

Sets 'syn iskeyword' in syntax/lf.vim to fix the missing lf keyword
highlighting in lines like 'map e :open; open' (first 'open' not
highlighted).

applies PR andis-sprinkis/lf-vim#21 by @joelim-work
closes: andis-sprinkis/lf-vim#14

Co-authored-by: Joe Lim <50560759+joelim-work@users.noreply.github.com>
Signed-off-by: Andis Spriņķis <andis@sprinkis.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/syntax/lf.vim b/runtime/syntax/lf.vim
index 2fe2859..0e877eb 100644
--- a/runtime/syntax/lf.vim
+++ b/runtime/syntax/lf.vim
@@ -3,7 +3,7 @@
 " Maintainer: Andis Sprinkis <andis@sprinkis.com>
 " Former Maintainer: Cameron Wright
 " URL: https://github.com/andis-sprinkis/lf-vim
-" Last Change: 5 Apr 2025
+" Last Change: 10 May 2025
 "
 " The shell syntax highlighting is configurable. See $VIMRUNTIME/doc/syntax.txt
 " lf version: 34
@@ -215,6 +215,7 @@
 
 unlet b:current_syntax
 exe 'syn include @Shell '.s:shell_syntax
+syn iskeyword @,-
 let b:current_syntax = "lf"
 
 syn region lfCommand matchgroup=lfCommandMarker start=' \zs:\ze' end='$' keepend transparent