feat: Power-off fix for the Steam Machine; the kernel pin is optional

Kernels >= 7.2 keep the firmware's S4/S5 wake bit on GPIO pin 18, so the
Steam Machine starts again right after powering off. Steam Machine
support now builds a DKMS module (patches/steamify-fremont-poweroff.c)
that clears it before power-off, for every kernel. The kernel pin is no
longer ticked by default. Module sources and patches move to patches/,
embedded by the single-file build.

ui/steamify-app.sh

@@ -2,7 +2,7 @@
 # Steamify CachyOS - get and start the app (v2), for `curl | bash`:
 #   curl -fsSL https://github.com/theupriser/steamify-cachyos/releases/latest/download/steamify-app.sh | bash
 # Downloads the newest release's app package (steamify-app.tar.gz: the app,
-# steamify.sh and lib/) to ~/.local/share/steamify/app, installs PySide6 if
+# steamify.sh, lib/ and patches/) to ~/.local/share/steamify/app, installs PySide6 if
 # it's missing, adds a launcher entry, and starts the app.
 # STEAMIFY_RELEASE=<tag> takes that release instead of the newest (the
 # v2-ui-preview build's copy of this script sets it). STEAMIFY_BRANCH=<branch>