refactor: The session sync and kernel headers scripts in patches/

patches/ensure-kernel-headers.sh

@@ -0,0 +1,14 @@
+#!/bin/bash
+# Installed by cachyos-gamescope-boot: install missing -headers for every
+# installed kernel, so DKMS builds leds-valve for it.
+set -u
+missing=()
+for k in $(pacman -Qqo /usr/lib/modules/*/pkgbase 2>/dev/null | sort -u); do
+    pacman -Q "${k}-headers" >/dev/null 2>&1 && continue
+    pacman -Si "${k}-headers" >/dev/null 2>&1 && missing+=("${k}-headers")
+done
+[[ ${#missing[@]} -eq 0 ]] && exit 0
+# Another pacman is running (e.g. an update): try again next boot.
+[[ -e /var/lib/pacman/db.lck ]] && { echo "pacman is busy, skipping"; exit 0; }
+echo "Installing missing kernel headers: ${missing[*]}"
+exec pacman -S --needed --noconfirm "${missing[@]}"