- Landing shows the tool tiles only when signed in and a sign-in card
otherwise; the login callback now returns to /.
- New public /help page: intro plus a per-tool Carbon accordion.
- Nav restructured to Home, {services}, divider, Help, Sign In/Out in
both the header and the side nav; the header right keeps only the
identity chip. Side-nav logo enlarged, border removed, spacing
equalised. Sign-out modal no longer flashes before it is defined.
- Per-deploy asset versioning (?v=) with immutable asset caching and
no-store HTML; help step lists show their numbers again.
- Tests updated and extended (48 total).
