Add .base.jsonl, .left.jsonl, and .right.jsonl patterns to the skip list in CheckLegacyJSONLFilename. These are legitimate git merge conflict artifacts that should not trigger a warning about multiple JSONL files. Fixes: bd-nsb 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <noreply@anthropic.com>