Add keyboard backlight adjustment

DynamicIsland/managers/SystemKeyboardBacklightController.swift

@@ -0,0 +1,66 @@
+import Foundation
+
+extension Notification.Name {
+    static let keyboardBacklightDidChange = Notification.Name("DynamicIsland.keyboardBacklightDidChange")
+}
+
+final class SystemKeyboardBacklightController {
+    static let shared = SystemKeyboardBacklightController()
+
+    var onBacklightChange: ((Float) -> Void)?
+
+    private let workerQueue = DispatchQueue(label: "com.atoll.keyboardBacklight", qos: .userInitiated)
+    private let notificationCenter = NotificationCenter.default
+    private var isRunning = false
+
+    private init() {}
+
+    func start() {
+        guard !isRunning else { return }
+        isRunning = true
+        notifyCurrentLevel()
+    }
+
+    func stop() {
+        guard isRunning else { return }
+        isRunning = false
+    }
+
+    func adjust(by delta: Float) {
+        let target = currentLevel + delta
+        setLevel(target)
+    }
+
+    func setLevel(_ value: Float) {
+        let clamped = max(0, min(1, value))
+        workerQueue.async {
+            do {
+                try KeyboardBrightnessSensor.setLevel(clamped)
+                let level = (try? KeyboardBrightnessSensor.currentLevel()) ?? clamped
+                self.emitChange(level: level)
+            } catch {
+                NSLog("⚠️ Failed to set keyboard backlight: \(error)")
+            }
+        }
+    }
+
+    var currentLevel: Float {
+        (try? KeyboardBrightnessSensor.currentLevel()) ?? 0
+    }
+
+    private func notifyCurrentLevel() {
+        workerQueue.async {
+            let level = (try? KeyboardBrightnessSensor.currentLevel()) ?? 0
+            self.emitChange(level: level)
+        }
+    }
+
+    private func emitChange(level: Float) {
+        guard isRunning else { return }
+        DispatchQueue.main.async { [weak self] in
+            guard let self, self.isRunning else { return }
+            self.onBacklightChange?(level)
+            self.notificationCenter.post(name: .keyboardBacklightDidChange, object: nil, userInfo: ["value": level])
+        }
+    }
+}