move apis into rom/modules/main for shell compatibility

sys/modules/opus/fs/gitfs.lua

@@ -0,0 +1,21 @@
+local git = require('opus.git')
+
+local fs = _G.fs
+
+local gitfs = { }
+
+function gitfs.mount(dir, repo)
+	if not repo then
+		error('gitfs syntax: repo')
+	end
+
+	local list = git.list(repo)
+	for path, entry in pairs(list) do
+		if not fs.exists(fs.combine(dir, path)) then
+			local node = fs.mount(fs.combine(dir, path), 'urlfs', entry.url)
+			node.size = entry.size
+		end
+	end
+end
+
+return gitfs