Disable xe Panel Replay on live boot for Panther Lake compatibility

[mijuny]

Fixes the live installer freezing on ASUS ExpertBook B9406CAA (and likely other Panther Lake laptops where the eDP panel has a broken Panel Replay exit/wake path). Symptom: one frame draws, then the display stays frozen until a VT switch forces a full modeset. You can't see the installer TUI to complete an install.

Panel Replay is Xe3-new, default-on in the xe driver. The Dell XPS on Panther Lake had a similar issue earlier that was resolved upstream (see basecamp/omarchy migration 1776781956.sh); the B9406CAA panel still needs the arg disabled.

The fix (xe.enable_panel_replay=0) is applied universally on the live ISO boot because bootloaders can't DMI-match before the kernel loads. It's harmless on machines that don't need it:

• Non-Panther-Lake hardware: the xe driver either isn't loaded or Panel Replay isn't supported on that GPU; the arg is a no-op.
• Panther Lake machines with working Panel Replay: they only lose a power-saving feature during the ~15 minute install

Companion hardware-match fix for the installed system (scoped narrowly to B9406 via DMI) is basecamp/omarchy#5435. Full diagnostic writeup and context: basecamp/omarchy#5423.

AI Disclaimer: Fixes found with help from Claude Code (Opus 4.7).