Bump version 0.1.5 → 0.1.6. Update CHANGELOG and README with
QueryExpander, LLMReranker, summaries_override, dashboard CLI,
tasks/ weight change, and retrieval metric improvements.

Add ruff per-file-ignores for dashboard/ and cli.py (E501, BLE001)
to suppress unfixable Rich markup line-length and intentional broad
exception catches.

Co-Authored-By: Claude Sonnet 4.6 (1M context) <noreply@anthropic.com>