CVE-2026-106560: Backstage: Improper repository path validation in a Scaffolder backend module

### Impact An authenticated user who can execute an affected template and control its repository file location may cause generated content to be written outside the task workspace, within locations writable by the Backstage backend process. ### Patches Patched in `@backstage/plugin-scaffolder-backend-module-confluence-to-markdown` version `0.3.25` ### Workarounds - Restrict execution of templates using the affected action to trusted users. - Remove or disable the affected action until the patched package is deployed.