feat(ui): redesign product surfaces

[StringKe]

Summary

• redesign the Console shell, responsive navigation, overview, and settings information hierarchy
• rework Hosted Auth into a connected product surface and simplify the sign-in composition
• rebuild the Nimbus landing page and shared UI primitives, including accessible dropdown and icon components
• synchronize all eight Lingui catalogs and compiled artifacts

Validation

• pnpm check
• pnpm test
• pnpm build
• pnpm run seo:audit
• pnpm run security:secret-scan
• pnpm --filter @xid-kit/console check
• pnpm --filter @xid-kit/console test
• pnpm --filter @xid-kit/site check
• git diff --check

Browser-based smoke and visual QA: SKIP by request. Production main CI will run the repository smoke gate after merge.