feat: HDMI refresh boost (Steam Machine, pinned kernel)

The pinned 7.1.6 kernel doesn't read the extra EDID block (HDMI Forum
EEODB) where monitors list their fast modes, and does no HDMI 2.1, so HDMI
displays often stay at 60 Hz. The new menu item reads the display's EDID
over DDC, calculates the highest rate that fits HDMI 2.0 at the desktop
resolution (rounded down to ten, plus the hundred below as a safe option),
tests each step live with a confirmation, and makes the confirmed ones
permanent through drm.edid_firmware (Limine, sdboot-manage or GRUB).

lib/menu.sh

@@ -5,7 +5,7 @@
 
 # Menu order. Components are turned on in this order and off in reverse;
 # gaming must come first (single user builds on it).
-COMPONENTS=(gaming boot theme glyphs single launcher cec machine kpin bios)
+COMPONENTS=(gaming boot theme glyphs single launcher cec machine kpin hdmi bios)
 # One-off actions rather than on/off components: never preselected, never
 # re-applied, not listed as on or off.
 ACTIONS=(bios)
@@ -14,8 +14,9 @@ declare -A PARENT=([boot]=gaming [kpin]=machine)
 # Never preselected on a first run: booting into the desktop is a choice,
 # gamescope is the default; HDMI-CEC is opt-in (it can wake the machine or
 # upset other devices on the TV, even on SteamOS), except on a Steam Machine,
-# which has CEC like on SteamOS.
-NO_PRESELECT=(boot cec)
+# which has CEC like on SteamOS. HDMI refresh boost needs someone at the
+# screen to confirm each step.
+NO_PRESELECT=(boot cec hdmi)
 
 declare -A LABEL=(
     [gaming]="SteamOS conversion: boot into gaming mode, Steam on the desktop"
@@ -27,6 +28,7 @@ declare -A LABEL=(
     [cec]="HDMI-CEC: use Steam with the TV remote, TV on/off with the PC (experimental)"
     [machine]="Steam Machine support: LED bar driver, hardware settings in Steam"
     [kpin]="Pin the kernel to $PINNED_KERNEL_VER (fixes rebooting after shutdown)"
+    [hdmi]="HDMI refresh boost: highest refresh your HDMI display runs"
     [bios]="Update BIOS"
 )
 declare -A CURRENT WANTED
@@ -34,6 +36,7 @@ declare -A CURRENT WANTED
 component_available() {
     case "$1" in
         machine|kpin) machine_available ;;
+        hdmi) hdmi_available ;;
         bios) bios_available ;;
     esac
 }