add file and redis loader

internal/loader/file.go

@@ -0,0 +1,30 @@
+package loader
+
+import (
+	"bytes"
+	"context"
+	"io"
+	"os"
+)
+
+type fileLoader struct {
+	filename string
+}
+
+func FileLoader(filename string) Loader {
+	return &fileLoader{
+		filename: filename,
+	}
+}
+
+func (l *fileLoader) Load(ctx context.Context) (io.Reader, error) {
+	data, err := os.ReadFile(l.filename)
+	if err != nil {
+		return nil, err
+	}
+	return bytes.NewReader(data), nil
+}
+
+func (l *fileLoader) Close() error {
+	return nil
+}