Add CSV export to search.py

[MakiDevelop]

What needs to be done

Add a --csv output option to search.py so results can be exported to spreadsheets.

Which file(s) to modify

• search.py — add CSV output format

Proposed approach

1. Add --csv flag to argparse
2. Use csv.writer (stdlib) to output results
3. Include columns: rank, similarity, signal_score, route_to, title, url, core_insight

Example usage

python3 search.py "AI agents" --csv > results.csv
python3 search.py "knowledge management" --csv -k 20

Acceptance criteria

• Uses stdlib csv module (no new dependencies)
• Header row included
• Works with both --rerank and default mode
• Adds a test case