Use the proper navbar-start/navbar-end structure with a horizontal menu
for the Report / View defects links, a red-dot brand mark echoing the
weak-point map, and a sticky shadowed bar. Rename the brand to the less
terse "Project Board Andon".
Drop the two-subdomain split (ADR 0004): report at /, view defects at
/defects, with a shared layout + header nav. Renames the dashboard page to
defects.vue and updates plan/README. Transparency over separation now that
auth gates everyone, and it removes the Coolify two-domain routing question.
