feat: Implement Multi-AI Architecture with Google Gemini provider and failover logic

chore: execute Sprint 38 technical debt resolution (Type Safety, Zod validation, Vitest, Mock LLM extracted)

feat: Genspark-Standard upgrade, MLOps audit fixes, and XAMLÉ branding

chore(api): add fast-levenshtein for Whisper WER calibration benchmark

feat(pedagogy): implementation of dynamic content infrastructure and evaluation criteria

fix: replace native fetch with axios to fix Node 20 ipv6 DNS ENOTFOUND in Docker

feat: admin auth login, real WhatsApp Cloud API, Cloudflare R2 storage

feat(security): API key auth, HMAC webhook verification, rate limiting, Zod validation

chore(build): use tsc --build to bust docker cache for new healthcheck

fix(redis): utilize ioredis and REDIS_URL for robust authenticated connections

feat(payment): integrate stripe checkout, webhooks, and worker dispatch

feat: implement AI document generation (mock, pdf, pptx) and worker integration

fix: resolve TS compilation errors in api service

Initial commit: Monorepo setup with React+Vite, Fastify, Prisma, and Docker Compose