chore: rewrite bbolt cachefile implements

never use returned byte slices outside the transaction, ref:
https://pkg.go.dev/go.etcd.io/bbolt#hdr-Caveats

common/utils/hash.go

@@ -0,0 +1,45 @@
+package utils
+
+import (
+	"crypto/md5"
+	"encoding/hex"
+)
+
+// HashType warps hash array inside struct
+// someday can change to other hash algorithm simply
+type HashType struct {
+	md5 [md5.Size]byte // MD5
+}
+
+func MakeHash(data []byte) HashType {
+	return HashType{md5.Sum(data)}
+}
+
+func MakeHashFromBytes(hashBytes []byte) (h HashType) {
+	if len(hashBytes) != md5.Size {
+		return
+	}
+	copy(h.md5[:], hashBytes)
+	return
+}
+
+func (h HashType) Equal(hash HashType) bool {
+	return h.md5 == hash.md5
+}
+
+func (h HashType) Bytes() []byte {
+	return h.md5[:]
+}
+
+func (h HashType) String() string {
+	return hex.EncodeToString(h.Bytes())
+}
+
+func (h HashType) Len() int {
+	return len(h.md5)
+}
+
+func (h HashType) IsValid() bool {
+	var zero HashType
+	return h != zero
+}