Arrow keys work without Fn outside Text Entry

; . , / are arrows on their own unless the foreground App is editing
text (App::textEntryActive); Fn + those keys are arrows everywhere.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EhqxQ49eCju4CzKYNjZzwT

src/apps/demo_app.h

@@ -19,6 +19,7 @@ class DemoApp : public App {
     explicit DemoApp(EventBus& bus) : bus_(bus) {}
     void onEnter() override;
     bool onKey(const KeyEvent& e) override;
+    bool textEntryActive() const override { return page_ == Page::Editor && !dialog_; }
     void draw(Canvas& c) override;
 
    private: