Explictly set the LFS remote URL for all forks

As the Gitea LFS server does not abstract access to LFS remotes
(see https://github.com/go-gitea/gitea/issues/17715), it is necessary to
explicitly set the main repository as LFS storage, including for forks.

.lfsconfig

@@ -0,0 +1,2 @@
+[lfs]
+	url = https://gitea.wildfiregames.com/0ad/0ad.git/info/lfs