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.

CLAUDE.md

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+# ROG Flow Z13 Trackpad Fix
+
+## Overview
+Fixes "Disable while typing" (DWT) + palm rejection on the ASUS ROG Flow Z13
+folio keyboard touchpad. The detachable keyboard connects via USB, which causes
+the touchpad to be misclassified as "external," blocking DWT in KDE Plasma.
+
+## Files
+- `fix-rog-z13-trackpad.sh` — install script (run with sudo)
+- `ROG_Flow_Z13_trackpad_fix_reference.txt` — full documentation
+- `rules/99-rog-z13-touchpad.rules` — standalone copy of the udev rule
+
+## System Files Created
+- `/etc/udev/rules.d/99-rog-z13-touchpad.rules` — marks touchpad as internal
+- `/etc/libinput/local-overrides.quirks` — marks keyboard as internal (optional)
+
+## Root Cause
+Systemd's `65-integration.rules` sets `ID_INPUT_TOUCHPAD_INTEGRATION=external`
+because the USB device is flagged `removable`. Libinput refuses DWT for external
+touchpads. The built-in libinput quirk (`50-system-asus.quirks`) only marks the
+keyboard as internal, not the touchpad — libinput has no `AttrTouchpadIntegration`
+quirk attribute.
+
+## Fix
+A udev rule at priority 99 overrides the property to `internal` after
+`65-integration.rules` (priority 65) sets it to `external`.
+
+## Key Details
+- USB VID:PID = `0b05:1a30`
+- Touchpad event device: `event8` (identified by `ID_INPUT_TOUCHPAD=1`)
+- Touchpad input name: `ASUSTeK Computer Inc. GZ302EA-Keyboard Touchpad`
+- The keyboard and touchpad share the same `LIBINPUT_DEVICE_GROUP`, enabling DWT pairing