KnowledgeVault AI module-spec M-07

M-07 gives company-authenticated field technicians a semantic search interface over the published knowledge base. A POST /api/query endpoint embeds the natural-language query via text-embedding-3-small (1536d), runs pgvector cosine similarity against knowledge_chunks WHERE is_published=true, ranks results by a fixed formula (cosine_similarity×0.7 + ground_truth_verified::int×0.2 + novelty_score×0.1), and returns the top-5 chunks with expert attribution, chunk type, field-verified badge, and rele