Add a Cheats menu tab with engine cheat buttons and unlimited-resource switches

The new Cheats tab exposes the engine's own cheat handlers as buttons:
give all items and weapons, toggle physics, next level and previous
level. Physics shows its state through the button highlight. The buttons
need a running game and show a message otherwise.

It also has four independent session-only switches for unlimited health,
energy, ammo and items (grenades and drugs). While a switch is on, its
resource is topped up every frame by qs_cheat_refill() from the new
engine patch 26. The switches are not saved to the config.

android/app/src/main/cpp/questshock_native.c

@@ -270,3 +270,19 @@ Java_de_ladkau_questshock_MenuOverlay_nativeSetControllerOptionsTabOpen(JNIEnv *
                                                                           jboolean open) {
     xr_input_set_controller_options_tab_open(open == JNI_TRUE);
 }
+
+// Cheats tab: same enqueue-only pattern as the other requests.
+JNIEXPORT void JNICALL
+Java_de_ladkau_questshock_MenuOverlay_nativeRequestCheat(JNIEnv *env, jclass clazz, jint cheatId) {
+    qs_config_request_cheat(cheatId);
+}
+
+JNIEXPORT jint JNICALL
+Java_de_ladkau_questshock_MenuOverlay_nativeGetCheatUnlimitedMask(JNIEnv *env, jclass clazz) {
+    return qs_config_cheat_unlimited_mask();
+}
+
+JNIEXPORT jboolean JNICALL
+Java_de_ladkau_questshock_MenuOverlay_nativeGetCheatPhysicsRunning(JNIEnv *env, jclass clazz) {
+    return qs_config_cheat_physics_running();
+}