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

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

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

fix(org-resolve): support legacy non-UUID custom IDs (e.g. default-org-id) + analytics orgId header

fix(audit): resolve technical debt + UX issues from 2026-05-11 audit

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 all remaining admin pages

chore: stabilization, audit fixes and project synchronization

feat: push notifications, CRM analytics, Fastify v5 upgrades, schema updates

fix: resolve stale type definitions and cleanup unused variables

feat: complete CRM module with ContactsPage and dynamic navigation