feat(billing): complete billing system, push notifications, and tech debt fixes
CognxSafeTrack +1: Claude Sonnet 4.6
- Usage tracking: instrument pedagogy, audio transcription, AI Agent mode (was silently untracked)
- EmailHandler: implement templates 2 (password reset), 3 (quota alert), 4 (monthly report)
- Quota alert: auto-queue email + push at 85% threshold via maybeQueueQuotaAlert
- Push notifications: PushHandler + send-push BullMQ job; sendPushToUser scoped by organizationId to prevent cross-tenant reads
- BillingPage: add credit recharge modal with 3 packs, null guard for missing orgId
- i18n: add nav.billing key in fr/en/es/pt locales
- Tests: billing.test.ts (10 tests), payments.test.ts (13 tests)
- Tech debt: fix empty catch blocks in ai-pedagogy.ts, exclude usage tokens from CRM API response, pass organizationId to generateChat in AIAgentHandler
- Docs: add backlog and business model to docs/business/
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
