Module discovery 

Discovery surface: orchestrated multi-stage retrieval.

discover is the headline pipeline (filter → score → expand → search → bullet-summarise); the other methods expose individual stages and the new phase12 pipeline steps:

• broad_discovery — multi-query broad search across collections
• semantic_focus — focused search within one collection
• promote_readme — README-quality chunk promotion
• compress_evidence — evidence compression into bullets
• build_answer_plan — bullet → section organisation
• render_llm_prompt — plan → final LLM prompt string