refactor: DKMS confs in patches/; an existing leds-valve DKMS override is kept and restored

patches/README.md

@@ -2,12 +2,14 @@
 
 Files Steamify builds or applies, kept out of the shell code so they can be
 read and reviewed on their own. `lib/*.sh` reads them with `patch_file
-<name>`; the single-file build (`.github/tools/bundle.sh`) embeds them.
+<name>` (piped through `fill KEY=value...` for `@KEY@` placeholders); the single-file build (`.github/tools/bundle.sh`) embeds them.
 
 | File | Used by | What |
 |---|---|---|
 | `steamify-fremont-poweroff.c` | `lib/fremont-poweroff.sh` (Steam Machine support) | Kernel module (DKMS): clears GPIO 18's S4/S5 wake bit before power-off, so the Steam Machine stays off with recent kernels |
 | `sync-steamos-session.sh` | `lib/login-manager.sh` (SteamOS conversion, plasma-login-manager) | The sync bridge: copies Steam's session choice from `zz-steamos-autologin.conf` into `plasmalogin.conf`'s `[Autologin]` |
 | `ensure-kernel-headers.sh` | `lib/steam-machine.sh` (Steam Machine support) | Run at boot: installs missing headers for every installed kernel |
+| `leds-valve-dkms.conf` | `lib/steam-machine.sh` (Steam Machine support) | `/etc/dkms` override: build the LED driver for DKMS's target kernel; appended to someone's own override, which is backed up and restored |
+| `steamify-fremont-poweroff.dkms.conf`, `steamify-cros-ec-cec.dkms.conf` | `lib/fremont-poweroff.sh`, `lib/cec.sh` | The DKMS modules' `dkms.conf` (`fill NAME=... VERSION=...`) |
 | `steamify-notifier.py` | `lib/update-notifier.sh` (Update notifications) | The daily check: notification and tray icon when there's a new release |
 | `cros-ec-cec-single-port.patch` | `lib/cec.sh` (HDMI-CEC) | Makes Valve's Steam Machine CEC driver find amdgpu's HDMI port |

patches/leds-valve-dkms.conf

@@ -0,0 +1,2 @@
+# Written by Steamify: build leds-valve for DKMS's target kernel, not the running one.
+MAKE[0]="make KVERSION=${kernelver}"

patches/steamify-cros-ec-cec.dkms.conf

@@ -0,0 +1,6 @@
+# Written by Steamify: Valve's cros_ec_cec, which knows the Steam Machine.
+PACKAGE_NAME="@NAME@"
+PACKAGE_VERSION="@VERSION@"
+BUILT_MODULE_NAME[0]="cros-ec-cec"
+DEST_MODULE_LOCATION[0]="/updates/dkms"
+AUTOINSTALL="yes"

patches/steamify-fremont-poweroff.dkms.conf

@@ -0,0 +1,6 @@
+# Written by Steamify: the Steam Machine powers off instead of booting up again.
+PACKAGE_NAME="@NAME@"
+PACKAGE_VERSION="@VERSION@"
+BUILT_MODULE_NAME[0]="@NAME@"
+DEST_MODULE_LOCATION[0]="/updates/dkms"
+AUTOINSTALL="yes"