runtime(openscad): add a filetype plugin

closes: #17902

Signed-off-by: Squibid <me@zacharyscheiman.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

Author: Squibid

.github/MAINTAINERS

@@ -243,6 +243,7 @@ runtime/ftplugin/nu.vim					@mrcjkb
 runtime/ftplugin/octave.vim				@dkearns
 runtime/ftplugin/ondir.vim				@jparise
 runtime/ftplugin/opencl.vim				@Freed-Wu
+runtime/ftplugin/openscad.vim                           @squibid
 runtime/ftplugin/openvpn.vim				@ObserverOfTime
 runtime/ftplugin/pascal.vim				@dkearns
 runtime/ftplugin/pbtxt.vim				@lakshayg

runtime/ftplugin/openscad.vim

@@ -0,0 +1,14 @@
+" Vim filetype plugin file
+" Language:    OpenSCAD (https://openscad.org)
+" Maintainer:  Zachary Scheiman <me@zacharyscheiman.com>
+" Last Change: 2025 Aug 3
+
+if exists('b:did_ftplugin')
+  finish
+endif
+let b:did_ftplugin = 1
+
+" Comments in openscad follow C/C++ syntax
+setlocal commentstring=//\ %s
+
+let b:undo_ftplugin = 'setl commentstring<'