feat: disable kernel updates in setup script

[Alpaca233]

Summary

• Adds apt-mark hold to setup_22.04.sh to pin the current kernel and generic kernel metapackages, preventing automatic kernel updates that can break driver/module compatibility
• Prints an unhold command for easy reversal

Test plan

• Run setup_22.04.sh on a fresh Ubuntu 22.04 install and verify kernel packages are held
• Verify apt-mark showhold lists the expected packages after setup
• Verify the printed unhold command correctly removes the holds

🤖 Generated with Claude Code

[Copilot]

Pull request overview

Adds kernel package holds to the Ubuntu 22.04 setup script to prevent automatic kernel upgrades that could break driver/module compatibility.

Changes:

• Hold Ubuntu kernel metapackages (linux-image-generic, linux-headers-generic, linux-generic) via apt-mark hold.
• Also hold the currently-running kernel image/headers packages and print an apt-mark unhold command for reversal.

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[Copilot]

The apt-mark hold call suppresses errors (2>/dev/null || true), but the next line always prints "Kernel packages held". If apt-mark fails (e.g., dpkg lock, missing package names, sudo issues), the script will claim success while not actually pinning the kernel. Consider removing the error suppression or checking the command exit status and printing a warning / aborting when the hold step fails; alternatively, validate with apt-mark showhold before printing the success message.

Suggested change

	sudo apt-mark hold \
	linux-image-generic linux-headers-generic linux-generic \
	"linux-image-$(uname -r)" "linux-headers-$(uname -r)" 2>/dev/null || true
	echo "Kernel packages held. Run 'sudo apt-mark unhold linux-image-generic linux-headers-generic linux-generic linux-image-$(uname -r) linux-headers-$(uname -r)' to re-enable."
	if sudo apt-mark hold \
	linux-image-generic linux-headers-generic linux-generic \
	"linux-image-$(uname -r)" "linux-headers-$(uname -r)"; then
	echo "Kernel packages held. Run 'sudo apt-mark unhold linux-image-generic linux-headers-generic linux-generic linux-image-$(uname -r) linux-headers-$(uname -r)' to re-enable."
	else
	echo "Warning: Failed to hold kernel packages; automatic kernel updates remain enabled." >&2
	fi