add modify placement listener mixin

src/main/java/com/vulpeus/kyoyu/client/mixins/litematica/SchematicPlacementMixin.java

@@ -0,0 +1,20 @@
+package com.vulpeus.kyoyu.client.mixins.litematica;
+
+//? if client {
+import fi.dy.masa.litematica.schematic.placement.SchematicPlacement;
+import fi.dy.masa.litematica.schematic.placement.SchematicPlacementManager;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
+
+@Mixin(SchematicPlacement.class)
+public class SchematicPlacementMixin {
+    @Inject(method = "onModified(Lfi/dy/masa/litematica/schematic/placement/SchematicPlacementManager;)V", at = @At("HEAD"), remap = false)
+    public void onModified(SchematicPlacementManager manager, CallbackInfo ci) {
+        // TODO
+        //  attention when connecting server is compatible
+        //  if (getClient() != null)
+    }
+}
+//?}

src/main/resources/kyoyu.client.mixins.json

@@ -5,6 +5,7 @@
   "compatibilityLevel": "${java_compatibility_level}",
   "client": [
     "litematica.GuiMainMenuMixin",
+    "litematica.SchematicPlacementMixin",
     "litematica.WidgetSchematicPlacementMixin"
   ],
   "injectors": {