netbird-install-update: add install/update script with remote deployment and auto-update timers

- Detects Netbird installation method (binary vs package manager)
- Replaces package manager installs with binary for consistency
- Supports single-host and multi-host SSH deployment
- Adds systemd timer for daily auto-updates with persistent scheduling
- Handles sudo password automation via --password flag or hosts file
- Connection-safe updates using background execution to survive SSH disconnects
- Fixes SELinux contexts and binary permissions automatically
- Provides detailed deployment summaries with per-host action tracking
- Includes SSH timeout handling to prevent hanging on unreachable hosts
- Color-coded output with icons for better readability

netbird-install-update/test-ssh.sh

@@ -0,0 +1,16 @@
+# Test SSH remote execution
+echo "=== Testing SSH remote execution ==="
+echo ""
+echo "Usage examples:"
+echo "  ./netbird-install-update.sh                          # Run locally"
+echo "  ./netbird-install-update.sh --timer                  # Run locally with auto-update timer"
+echo "  ./netbird-install-update.sh --ssh user@host           # Deploy to remote host"
+echo "  ./netbird-install-update.sh --ssh user@host --timer   # Deploy to remote host with timer"
+echo ""
+echo "The -ssh flag will:"
+echo "1. Copy this script to the remote host via scp"
+echo "2. Execute it remotely with sudo"
+echo "3. Pass through any other flags (like --timer)"
+echo "4. Clean up the remote copy after execution"
+echo ""
+echo "Script is ready for testing!"