[WIP] chore(deps-major): migrate @react-router/dev to 8.0.1 2026-06-24

[Copilot]

Thanks for asking me to work on this. I will get started on it and keep this PR's description up to date as I form a plan and make progress.

Original prompt

Migrate the dependency '@react-router/dev' to 8.0.1 on a new branch and open ONE pull request titled 'chore(deps-major): migrate @react-router/dev to 8.0.1 2026-06-24'. This is a KNOWN BREAKING major bump — work through the migration carefully using this assessment as the spec:

FRAMEWORK-MODE major (7.13.1 → 8.0.1; 8.0.1 is a patch within v8, migration story unchanged). v8 requires node 22.22+, react/react-dom >=19.2.7 (app pins ^19.1.0 — UNADDRESSED GAP), vite >=7, and react-router/@react-router/dev pinned together at ^8. future.v8_viteEnvironmentApi already enabled. Must move in LOCKSTEP with react-router + @react-router/dev + vite + react. Run react-router typegen + tsc -b after.

Apply the code changes the breaking changes require, run the project's install + test/build, and make sure it is green before opening the PR. Keep the change scoped to THIS migration only (do not bump unrelated dependencies, do not refactor). Do NOT merge.