(BE-58,,59): extend db schema & build stock transfer api

- Extend DB schema for stock transfers
- Build stock transfer API (create,)

internal/utils/time.go

@@ -0,0 +1,25 @@
+package utils
+
+import (
+	"time"
+	"errors"
+)
+
+// ParseDateString mengubah string "YYYY-MM-DD" menjadi time.Time
+func ParseDateString(dateStr string) (time.Time, error) {
+	if dateStr == "" {
+		return time.Time{}, errors.New("date string is empty")
+	}
+
+	parsed, err := time.Parse("2006-01-02", dateStr)
+	if err != nil {
+		return time.Time{}, errors.New("invalid date format, expected YYYY-MM-DD")
+	}
+
+	return parsed, nil
+}
+
+// FormatDate mengubah time.Time menjadi string "YYYY-MM-DD"
+func FormatDate(t time.Time) string {
+	return t.Format("2006-01-02")
+}