KnowledgeVault AI module-spec M-03

M-03 delivers the offline intelligence pipeline that pre-computes product knowledge scaffolding before any expert session begins. For each SKU in the products catalog, a Supabase Edge Function invokes Gemini 2.5 Pro with the product image, catalog description, and spec sheet to generate a calibrated ordered question set (3-5 questions), a product context summary, and key knowledge vectors. Results are cached in product_pre_seeds — one row per product — and are re-generated automatically when spe