chore(lune): include frktest-powered test runner

.lune/test.luau

@@ -0,0 +1,24 @@
+--> Run tests using frktest runner
+
+local fs = require("@lune/fs")
+local process = require("@lune/process")
+
+local frktest = require("@pkg/frktest")
+
+-- HACK: Cast require to allow for dynamic paths in strict mode
+-- A more proper solution would be to use luau.load instead, but
+-- frktest requires its global state to be modified by test suites
+local require = require :: (path: string) -> () -> ()
+
+if process.args[1] ~= nil then
+	require("../tests/" .. process.args[1])()
+else
+	for _, test in fs.readDir("tests") do
+		require("../tests/" .. test)()
+	end
+end
+
+frktest.reporters.lune.init()
+if not frktest.core.run() then
+	process.exit(1)
+end