Upgrade React Router packages for CVE fixes

[kentcdodds]

Upgrades the direct React Router package family and related direct dev tools:

• react-router to 7.16.0
• @react-router/dev to 7.16.0
• @react-router/node to 7.16.0
• @react-router/express to 7.16.0
• react-router-auto-routes to 0.8.4
• react-router-devtools to 6.2.1

Also updates the auth callback loader test helper for React Router 7.16's server loader args (url/pattern).

Test Plan

• npm list react-router @react-router/dev @react-router/node @react-router/express react-router-devtools react-router-auto-routes --depth=1
• node --input-type=module -e "...npm audit --json summary..." (still exits with existing audit findings; the React Router CVE package family is resolved to 7.16.0. Remaining audit entries include unrelated packages plus react-router-devtools's existing react-d3-tree/uuid advisory, for which npm suggests downgrading to react-router-devtools@1.0.0 rather than a newer patched release.)
• set -a && . ./.env.example && set +a && npx prisma migrate deploy && npx prisma generate --sql && npm run typecheck && npm run build && npm run test -- --run

Checklist

• Tests updated
• Docs updated

Screenshots

N/A - dependency/security update only.