Ignore GitHub Copilot migration files

Add GitHub Copilot session migration files to .gitignore

Author: yutamago

Global/JetBrains.gitignore

@@ -81,3 +81,6 @@ http-client.private.env.json
 # Apifox Helper cache
 .idea/.cache/.Apifox_Helper
 .idea/ApifoxUploaderProjectSetting.xml
+
+# Github Copilot persisted session migrations, see: https://github.com/microsoft/copilot-intellij-feedback/issues/712#issuecomment-3322062215
+.idea/**/copilot.data.migration.*.xml