KnowledgeVault AI module-spec M-08

M-08 enables company-authenticated field technicians to query a named AI expert persona and receive a GPT-4o synthesised first-person answer attributed to that expert. The module adds GET /api/virtual-experts (listing all published experts) and POST /api/virtual-experts/[id]/query (scoped pgvector similarity search over the expert published knowledge chunks, GPT-4o synthesis with strict no-fabrication instruction, field_verified_badge logic, and field_queries audit logging). Two React screens co