feat: transparent support for ddcutil on desktop

[jamerrq]

Description

This PR updates the omarchy-brightness-display script to provide transparent, default support for desktop monitors using ddcutil.

Currently, default XF86MonBrightnessDown/XF86MonBrightnessUp keybindings fail on desktops due to the lack of internal backlights exposed through /sys/class/backlight.

By adding a simple has_backlight heuristic, the script now automatically falls back to ddcutil for executing brightness up/down steps.

Details

• Checks for brightness devices dynamically on script launch.
• If no laptop backlight is detected, parses the +5% / 5%- step format manually.
• Caches the value temporarily in /tmp/ddcutil_brightness_omarchy and fires omarchy-swayosd-brightness immediately so that visual OSD feedback is instantaneous.
• Runs ddcutil setvcp 10 asynchronously in the background.

This brings an out-of-the-box solution for both laptops (native brightnessctl) and desktop monitors (ddcutil), while still allowing users to view the cool SwayOSD notifications.

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[felipe3dfx]

Hey @jamerrq — I took a different cut at the same problem in #5282, wanted to flag it here so you and the maintainers see both approaches side by side.

Main differences from yours:

• Install hook + migration so users don't have to install ddcutil and set up the i2c group / udev rule by hand.
• Blocking flock (instead of -n) to fix silent drops during rapid bursts.
• Debounce pattern — one setvcp per gesture — which cuts monitor NVRAM wear and keeps the OSD in sync. KDE PowerDevil does the same thing for the same reasons (D8626).
• Iteration over all detected i2c buses for multi-monitor setups.

Not trying to replace yours — just want to make sure basecamp sees both takes. Happy to merge ideas in either direction.

[jamerrq]

Hi @felipe3dfx. Thanks for the heads up and for linking your PR.

Your approach is definitely much more robust. I really appreciate the debounce pattern to protect the monitor's NVRAM—that’s an excellent and critical catch that I hadn't considered. Also, dynamic detection of i2c buses and automatically handling the migration/installation hooks makes it a much better fit for Omarchy's "it just works" philosophy.

I'm more than happy to close this PR in favor of #5282 so the maintainers can focus entirely on yours, as it clearly handles all the edge cases properly.