Refactor golden image handling in backup upload process</message>

<message>Update the _set_golden_from_path function to improve the handling of existing golden image files. Replace the existing unlink logic with a more robust method that safely removes files or broken symlinks using the missing_ok parameter. This change enhances the reliability of the backup upload process by ensuring that stale references are properly cleared before setting a new golden image path.

emmc-provisioning/cloud-init/fileserver/bootstrap.sh

@@ -0,0 +1,4 @@
+#!/bin/bash
+# Minimal bootstrap script for cloud-init first boot (test).
+set -e
+echo "[$(date -Iseconds)] test completed" | tee -a /var/log/cloud-init-bootstrap.log

emmc-provisioning/cloud-init/fileserver/bootstrap.sh.example

@@ -0,0 +1,19 @@
+#!/bin/bash
+# Example bootstrap script run by cloud-init at first boot.
+# Copy to bootstrap.sh, edit as needed, and place in your portal files (e.g. first-boot/)
+# so it is served at http://YOUR_SERVER:5000/files/bootstrap.sh
+#
+# Cloud-init downloads this and runs it as root. Add your first-boot logic here:
+# - Install packages, apply config, run first-boot.sh from this repo, etc.
+
+set -e
+echo "[$(date -Iseconds)] Bootstrap script started."
+
+# Example: run the full first-boot flow from your file server (same as user-data-remote-gnss.example)
+# FILE_SERVER="http://10.20.50.1:5000/files/first-boot"
+# curl -fsSL "$FILE_SERVER/first-boot.sh" -o /tmp/first-boot.sh
+# curl -fsSL "$FILE_SERVER/first-boot.conf" -o /tmp/first-boot.conf
+# chmod +x /tmp/first-boot.sh
+# /tmp/first-boot.sh
+
+echo "[$(date -Iseconds)] Bootstrap script finished."