runtime: set 'cpoptions' for line-continuation in various runtime files

closes: #17121

Signed-off-by: Eisuke Kawashima <e-kwsm@users.noreply.github.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/ftplugin/heex.vim b/runtime/ftplugin/heex.vim
index becc071..2f53d22 100644
--- a/runtime/ftplugin/heex.vim
+++ b/runtime/ftplugin/heex.vim
@@ -2,12 +2,16 @@
 " Language: HEEx
 " Maintainer:	Mitchell Hanberg <vimNOSPAM@mitchellhanberg.com>
 " Last Change: 2022 Sep 21
+" 2025 Apr 16 by Vim Project (set 'cpoptions' for line continuation, #17121)
 
 if exists("b:did_ftplugin")
   finish
 endif
 let b:did_ftplugin = 1
 
+let s:cpo_save = &cpo
+set cpo&vim
+
 setlocal shiftwidth=2 softtabstop=2 expandtab
 
 setlocal comments=:<%!--
@@ -25,3 +29,6 @@
 	\	      '<\@<=\([^/!][^ \t>]*\)[^>]*\%(>\|$\):<\@<=/\1>'
   let b:undo_ftplugin ..= " | unlet! b:match_ignorecase b:match_words"
 endif
+
+let &cpo = s:cpo_save
+unlet s:cpo_save