Add the public-facing shared session page at /share/:shareToken that
renders shared sessions without authentication. Includes error handling
for 401 (redirect to login), 403 (access denied), 404 (not found),
and 410 (expired). The page features a minimal header, session metadata,
SessionTimeline component, and a new SharedSessionTreePreview component
that renders the decision tree structure with the path taken highlighted.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
d7641f2f84