Move the synthetic-input toggle to Controllers under Debug details

"Forward synthetic test input" is a controller-debug aid, so it now lives in the
Controllers panel (gated behind Debug details, disabled until the XInput hook is
attached) instead of the Injection panel. ControllersPanel owns the flag and exposes
test_input(); main feeds it into InjectionPanel::set_test_input each frame, so the
existing synthetic-pad substitution in publish() is unchanged.

Verified: x64 build green; review (default view no longer shows it in Injection;
appears in Controllers under Debug details).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

host/src/main.cpp

@@ -144,6 +144,7 @@ int run()
 		}
 #endif
 		input->poll();
+		injection.set_test_input(controllers.test_input()); // toggle lives in the Controllers panel
 		injection.publish(input->pads());
 		injection.tick(); // refresh target liveness before the mirror panels read game_hwnd()
 		const HWND game = injection.game_hwnd();