fix(ui): link navbar brand to landing page

[phongndo]

Summary

• Make the navbar brand a home link on every non-landing page so users can return to the start of the delivery workflow.
• Keep the brand as non-interactive text on the landing page.

Motivation

• Onboarding and route workflow pages did not provide a consistent way to return to the landing page from the top navigation.

Changes

• Frontend: use the current pathname to distinguish the landing page from internal routes.
• Frontend: render an accessible Next.js link to / on internal routes while preserving the existing brand typography and overflow behavior.
• UI before/after: previously the brand was static text on every route; it now links home on internal routes with no visual styling change. No screenshot is included because the rendered appearance is unchanged.
• Backend, infrastructure, and documentation: no changes.

Validation

Frontend

• npm --prefix app/ui run lint — passed with zero warnings.
• npm --prefix app/ui run format:check — passed; all files match Prettier formatting.
• npm --prefix app/ui run typecheck — passed.
• npm --prefix app/ui run test — passed; 24 test files and 115 tests.
• npm --prefix app/ui run build — passed; Next.js compiled and generated all 16 static pages.
• npm --prefix app/mobile run lint — not run; mobile is unchanged.
• npm --prefix app/mobile run typecheck — not run; mobile is unchanged.

Playwright end-to-end tests were not run; the focused frontend checks and production build cover this scoped navigation change.

Backend

• cmake --preset dev
• .github/scripts/check-backend-static.sh build/dev
• cmake --build --preset dev --parallel
• ctest --preset dev --output-on-failure --no-tests=error -LE 'e2e|docker'
• docker compose -f deploy/compose/docker-compose.arm64.yml --env-file deploy/env/http-server.arm64.env config

Backend checks were not run because this change only affects the UI navbar component.

Risk

• Low. The change is limited to navbar rendering and client-side navigation; it does not alter APIs, stored data, styling, or workflow state.
• The landing page intentionally remains non-interactive to avoid a self-link.

Rollout and Recovery

• Deploy through the normal frontend release process; no migration or feature flag is required.
• Revert commit 63d383d4955b1e2349b3d0508b237f4b41f6c669 to restore the prior static brand behavior.

High-Signal PR Checklist

• The summary states the user-visible or operational outcome, not just file names.
• The motivation explains why this change is needed now.
• The change list separates frontend, backend, infrastructure, and documentation work where applicable.
• Validation includes exact commands run, relevant output, and any checks intentionally skipped.
• Risks, migrations, feature flags, and rollback steps are called out when relevant.
• Screenshots, request/response examples, or before/after notes are included for behavior changes.

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