support multi-module (#4)

* add multimodule
* re-package modules

server/internal/repo/fs/helper_test.go

@@ -0,0 +1,22 @@
+package fs
+
+import (
+	"slices"
+)
+
+const (
+	nonWritableDir = "/usr/lib"
+)
+
+type sampleData struct {
+	data []byte
+}
+
+func (sd *sampleData) UnmarshalBinary(data []byte) error {
+	sd.data = slices.Clone(data)
+	return nil
+}
+
+func (sd sampleData) MarshalBinary() (data []byte, err error) {
+	return sd.data, nil
+}