feat: agentic platform — text-to-sql, pedagogy advisor, security hardening & performance

feat: Claude Sonnet 4.6 provider + Stripe billing automation

feat: backlog P0→P3 — toast system, payments, tenant isolation, feedback handler, i18n parity

feat: implement whatsapp templates management with security hardening, audit logs, and crm integration

feat: B2B SaaS Multi-tenant architecture & Tech Debt Resolution