ciguard: discover_pipeline_files follows symlinks out of scan root

ciguard is a static security auditor for CI/CD pipelines. From 0.8.0 to 0.8.1 , the discover_pipeline_files() function in src/ciguard/discovery.py walks a directory tree following symlinks, with cycle protection via tracking visited resolved paths. An attacker who can plant a symlink in a directory the user (or AI agent) scans can cause discovery to walk into the symlink target and return paths to pipeline-shaped files outside the requested root. This vulnerability is fixed in 0.8.2.