feat: polish scenarios and stabilize keyboard layout height

Add preset-driven polish scenarios (Settings, onboarding, ScenarioChip)
with ScenarioPrompt and style directives; drive keyboard height from
content (240pt) and use viewIsAppearing encapsulated-height offset for
smoother keyboard switches; remove redundant StatusBadge and hide system
dictation via hasDictationKey.

OSGKeyboardShared/Services/AppGroupConfigDarwin.swift

@@ -0,0 +1,22 @@
+// AppGroupConfigDarwin.swift
+// OSGKeyboard · Shared
+//
+// Cross-process Darwin notification when App Group config changes
+// (translation target, cloud-polish toggle, etc.). Lets the host app
+// and keyboard extension pick up writes without waiting on the 1 Hz poll.
+
+import Foundation
+
+public enum AppGroupConfigDarwin {
+    public static let notificationName = "com.osgkeyboard.config.changed"
+
+    public static func postConfigChanged() {
+        CFNotificationCenterPostNotification(
+            CFNotificationCenterGetDarwinNotifyCenter(),
+            CFNotificationName(notificationName as CFString),
+            nil,
+            nil,
+            true
+        )
+    }
+}