Implement MoveFile functionality in FileManager and corresponding tests

server/internal/storage/filesystem.go

@@ -10,6 +10,7 @@ import (
 type fileSystem interface {
 	ReadFile(path string) ([]byte, error)
 	WriteFile(path string, data []byte, perm fs.FileMode) error
+	MoveFile(src, dst string) error
 	Remove(path string) error
 	MkdirAll(path string, perm fs.FileMode) error
 	RemoveAll(path string) error
@@ -38,6 +39,21 @@ func (f *osFS) WriteFile(path string, data []byte, perm fs.FileMode) error {
 	return os.WriteFile(path, data, perm)
 }
 
+// MoveFile moves the file from src to dst, overwriting if necessary.
+func (f *osFS) MoveFile(src, dst string) error {
+	if err := os.Rename(src, dst); err != nil {
+		if os.IsExist(err) {
+			// If the destination exists, remove it and try again
+			if err := os.Remove(dst); err != nil && !os.IsNotExist(err) {
+				return err
+			}
+			return os.Rename(src, dst)
+		}
+		return err
+	}
+	return nil
+}
+
 // Remove deletes the file at the given path.
 func (f *osFS) Remove(path string) error { return os.Remove(path) }