DodoApp: Use picocss for UI

Change-Id: I2d610c4f57e4dfbbe566a7c7f82147443e0106f1
diff --git a/core/installer/soft/repoio.go b/core/installer/soft/repoio.go
index 872a5cf..a0b0459 100644
--- a/core/installer/soft/repoio.go
+++ b/core/installer/soft/repoio.go
@@ -343,3 +343,13 @@
 	defer r.Close()
 	return io.ReadAll(r)
 }
+
+func WriteFile(repo RepoFS, path, contents string) error {
+	w, err := repo.Writer(path)
+	if err != nil {
+		return err
+	}
+	defer w.Close()
+	_, err = io.WriteString(w, contents)
+	return err
+}