feat(i18n): complete admin app internationalization across all pages

fix(audit): resolve all remaining technical debt issues

fix(security): resolve critical and high technical debt from audit

feat(crm-ux): tag management, unread badge, handoff release UI

refactor(debt): resolve all 10 technical debt items from audit

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

feat: wire i18n to dashboard, settings, users — complete locale files

feat: migrate to multi-tenant SaaS architecture with JWT auth and BullMQ notifications

ux: clear messages for tenant selection in admin dashboard

Refactor: Technical Debt Repayment (Clean Dashboard, Strict Typing, Pino Logging, SQL Migration)