rootfs: Add udev rule for AYANEO 3 magic module controls

[matmartinez]

Prerequisite for the AYANEO magic-modules quick-bar plugin, as requested in #528: grants unprivileged access to the sysfs controls the plugin drives — eject/reset on the hid-ayaneo driver and controller_power on the mainline ayaneo-ec driver.

Notes:

• udev can't set permissions on sysfs attributes via MODE/uaccess (device nodes only), hence the RUN+chmod form. The HID device rebinds on every controller power cycle, so the rule matches add|bind.
• Went with 0666 since these are local physical controls with no data exposure and there's no cross-distro group to target; happy to switch to a group-write model if you prefer one.
• Verified on an AYANEO 3 running Bazzite 44: with this rule the plugin performs the full eject → power-cut → reinsert → repower cycle unprivileged.

The plugin itself: https://github.com/matmartinez/ayaneo-3-bazzite-compat/tree/main/ogui-plugin — registry PR to OpenGamepadUI-plugins to follow once this lands. (While building it I also hit #535, which affects all quick-bar plugins in overlay mode.)

[matmartinez]

Revised rule verified on hardware (AYANEO 3, Bazzite 44): all three attributes come up 0666 on a natural driver rebind (the TEST== existence matches fire correctly — they're stat-based, so the write-only attrs don't trip them), and an unprivileged user has write access. Also confirmed across a manual udevadm trigger for the ayaneo-ec add rule.