feat: add laptop/display brightness modulation

kernel/src/ACPI/AcpiVideo.hpp

@@ -0,0 +1,23 @@
+/*
+    * AcpiVideo.hpp
+    * ACPI video extensions (_BCL/_BCM/_BQC) panel brightness fallback
+    * Copyright (c) 2026 Daniel Hammer
+*/
+
+#pragma once
+#include <cstdint>
+
+namespace Hal {
+    namespace AcpiVideo {
+
+        // Panel brightness through the firmware's ACPI video output device,
+        // for machines no native backlight driver covers (a panel wired to a
+        // discrete GPU, a GPU Montauk has no driver for). percent < 0 queries;
+        // otherwise the nearest level the firmware lists is selected. Returns
+        // the resulting 0..100, -1 when the firmware has no brightness
+        // methods, -2 when evaluating them failed. Discovery runs on first
+        // use. May sleep (AML).
+        int Brightness(int percent);
+
+    };
+};