feat(keyboard): unify assistant voice and AI workflows

Merge dictation and AI controls into one assistant surface, preserve safe insertion and clipboard actions, and align settings and tests with the new flow.

OSGKeyboardExt/Views/LastInputEditView.swift

@@ -6,7 +6,7 @@ import OSGKeyboardShared
 
 struct LastInputEditView: View {
     private enum Layout {
-        static let primaryButtonHeight: CGFloat = 50
+        static let primaryButtonHeight = KeyboardChromeLayout.assistantActionCapsuleHeight
         static let primaryButtonWidth: CGFloat = primaryButtonHeight * 3
     }
 
@@ -139,6 +139,7 @@ struct LastInputEditView: View {
             }
             .buttonStyle(.plain)
             .disabled(primaryDisabled)
+            .accessibilityIdentifier(primaryAccessibilityIdentifier)
             .accessibilityLabel(Text(primaryAccessibilityLabel))
             helperText(rightHelper)
         }
@@ -239,6 +240,17 @@ struct LastInputEditView: View {
         return ExtL10n.string("keyboard.edit.stop")
     }
 
+    private var primaryAccessibilityIdentifier: String {
+        switch state.editSession {
+        case .listening:
+            return "assistant.edit.stop"
+        case .review:
+            return "assistant.edit.confirm"
+        default:
+            return "assistant.edit.primary"
+        }
+    }
+
     private var reviewSwipeGesture: some Gesture {
         DragGesture(minimumDistance: 12)
             .onEnded { value in