Artifact generation fails due to missing .DS_Store in the branding directories

Nightly builds are failing, and I think the solution is we need a .DS_Store for them:

 0:07.67 W Traceback (most recent call last):
 0:07.67 W   File "<frozen runpy>", line 198, in _run_module_as_main
 0:07.67 W   File "<frozen runpy>", line 88, in _run_code
 0:07.67 W   File "/var/tmp/build/firefox-22a770a7fcfd/python/mozbuild/mozbuild/action/package.py", line 137, in <module>
 0:07.67 W     sys.exit(main(sys.argv[1:]))
 0:07.67 W              ~~~~^^^^^^^^^^^^^^
 0:07.67 W   File "/var/tmp/build/firefox-22a770a7fcfd/python/mozbuild/mozbuild/action/package.py", line 125, in main
 0:07.67 W     return _make_dmg(
 0:07.67 W         cwd,
 0:07.67 W     ...<5 lines>...
 0:07.67 W         args.volume_name,
 0:07.67 W     )
 0:07.67 W   File "/var/tmp/build/firefox-22a770a7fcfd/python/mozbuild/mozbuild/action/package.py", line 70, in _make_dmg
 0:07.67 W     return dmg_action.main(args) or 0
 0:07.67 W            ~~~~~~~~~~~~~~~^^^^^^
 0:07.67 W   File "/var/tmp/build/firefox-22a770a7fcfd/python/mozbuild/mozbuild/action/make_dmg.py", line 56, in main
 0:07.67 W     dmg.create_dmg(
 0:07.67 W     ~~~~~~~~~~~~~~^
 0:07.67 W         source_directory=Path(options.inpath),
 0:07.67 W         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 0:07.67 W     ...<5 lines>...
 0:07.67 W         mkfshfs_tool=mkfshfs_tool,
 0:07.67 W         ^^^^^^^^^^^^^^^^^^^^^^^^^^
 0:07.67 W     )
 0:07.67 W     ^
 0:07.67 W   File "/var/tmp/build/firefox-22a770a7fcfd/python/mozbuild/mozpack/dmg.py", line 198, in create_dmg
 0:07.67 W     shutil.copyfile(source, full_target)
 0:07.67 W     ~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^
 0:07.67 W   File "/usr/lib/python3.13/shutil.py", line 260, in copyfile
 0:07.67 W     with open(src, 'rb') as fsrc:
 0:07.67 W          ~~~~^^^^^^^^^^^
 0:07.67 W FileNotFoundError: [Errno 2] No such file or directory: '/var/tmp/build/firefox-22a770a7fcfd/browser/branding/tb-nightly/dsstore'
 0:07.69 E gmake[3]: *** [/var/tmp/build/firefox-22a770a7fcfd/toolkit/mozapps/installer/packager.mk:134: make-package-internal] Error 1
 0:07.69 E gmake[2]: *** [/var/tmp/build/firefox-22a770a7fcfd/toolkit/mozapps/installer/packager.mk:138: make-package] Error 2
 0:07.69 E gmake[1]: *** [/var/tmp/build/firefox-22a770a7fcfd/config/rules.mk:357: default] Error 2
 0:07.69 E gmake: *** [/var/tmp/build/firefox-22a770a7fcfd/browser/build.mk:6: package] Error 2
 0:07.79 W 0 compiler warnings present.

@brizental how is this .dmg file used? What items are present on it? Once we know what we need to include in the .DS_Store we can easily generate it, I've done it a few times in the past, and I'm pretty sure we have the command I used back then in some issue comment.