Add ROG Flow Z13 trackpad DWT/palm rejection fix

Udev rule to override ID_INPUT_TOUCHPAD_INTEGRATION from external to
internal for the Z13 folio touchpad, plus reference docs and install
script.

fix-rog-z13-trackpad.sh

@@ -0,0 +1,104 @@
+#!/bin/bash
+#
+# fix-rog-z13-trackpad.sh
+# Enables "Disable while typing" (DWT) + palm rejection on the
+# ASUS ROG Flow Z13 folio keyboard touchpad.
+#
+# Usage:  ./fix-rog-z13-trackpad.sh
+#         (must be run as root)
+#
+# Tested on: CachyOS / Arch Linux, KDE Plasma 6, Wayland
+# Applies to: ROG Flow Z13 (2023 & 2025 models, USB 0b05:1a30)
+
+set -euo pipefail
+
+if [ "$(id -u)" -ne 0 ]; then
+  echo "ERROR: This script must be run as root."
+  echo "Usage: sudo ./fix-rog-z13-trackpad.sh"
+  exit 1
+fi
+
+echo "=== ROG Flow Z13 Trackpad Fix ==="
+echo ""
+
+# ──────────────────────────────────────
+# 1. udev rule — mark touchpad as internal
+# ──────────────────────────────────────
+UDEV_RULE="/etc/udev/rules.d/99-rog-z13-touchpad.rules"
+
+if [ -f "$UDEV_RULE" ]; then
+  echo "[SKIP] $UDEV_RULE already exists"
+else
+  echo "[CREATE] $UDEV_RULE"
+  cat > "$UDEV_RULE" << 'EOF'
+# ROG Flow Z13 folio keyboard touchpad integration override
+#
+# The Z13's detachable folio keyboard connects via USB (0b05:1a30).
+# The touchpad on this device is correctly exposed as a touchpad, but
+# udev marks it as ID_INPUT_TOUCHPAD_INTEGRATION=external because the
+# USB device is flagged as "removable" (it's a detachable keyboard).
+#
+# Libinput refuses to enable "Disable While Typing" (DWT) for touchpads
+# marked as external, which greyed out the checkbox in KDE Plasma.
+#
+# This rule overrides the integration type to "internal" for the Z13
+# touchpad only, which allows DWT pairing with the keyboard (already
+# marked internal via the libinput quirk in 50-system-asus.quirks).
+
+ACTION=="add|change", SUBSYSTEM=="input", \
+  ENV{ID_VENDOR_ID}=="0b05", ENV{ID_MODEL_ID}=="1a30", \
+  ENV{ID_INPUT_TOUCHPAD}=="1", \
+  ENV{ID_INPUT_TOUCHPAD_INTEGRATION}="internal"
+EOF
+fi
+
+# ──────────────────────────────────────
+# 2. libinput quirk — mark keyboard as internal (belt-and-suspenders)
+# ──────────────────────────────────────
+LIBINPUT_QUIRKS="/etc/libinput/local-overrides.quirks"
+
+# Only create if it doesn't exist; if it does, it may have user customizations
+if [ -f "$LIBINPUT_QUIRKS" ]; then
+  echo "[SKIP] $LIBINPUT_QUIRKS already exists (not overwriting)"
+else
+  echo "[CREATE] $LIBINPUT_QUIRKS"
+  mkdir -p /etc/libinput
+  cat > "$LIBINPUT_QUIRKS" << 'EOF'
+[ROG Flow Z13 All USB Keyboards]
+MatchUdevType=keyboard
+MatchBus=usb
+MatchVendor=0x0B05
+AttrKeyboardIntegration=internal
+EOF
+fi
+
+# ──────────────────────────────────────
+# 3. Apply udev changes
+# ──────────────────────────────────────
+echo ""
+echo "[APPLY] Reloading udev rules..."
+udevadm control --reload-rules
+
+echo "[APPLY] Triggering udev for existing devices..."
+udevadm trigger --subsystem-match=input
+
+echo ""
+echo "=== DONE ==="
+echo ""
+echo "The fix has been applied. To activate it:"
+echo ""
+echo "  1. Log out and log back in (or reboot)"
+echo "  2. Open System Settings -> Touchpad"
+echo "  3. Check \"Disable touchpad when typing\""
+echo ""
+echo "The checkbox should now be available. If the touchpad already"
+echo "feels better at rejecting palm brushes while typing — that's"
+echo "expected. DWT and improved palm rejection both activate when"
+echo "the touchpad is recognized as internal."
+echo ""
+echo "To undo this fix later, run:"
+echo "  sudo rm /etc/udev/rules.d/99-rog-z13-touchpad.rules"
+echo "  sudo rm /etc/libinput/local-overrides.quirks"
+echo "  sudo udevadm control --reload-rules"
+echo "  sudo udevadm trigger --subsystem-match=input"
+echo ""