Reference turbopack root widening bug

During CreatorTrack round-4 merge, an agent had added turbopack.root: "/home/justinwieb" to next.config.ts as a workaround for the worktree symlink issue. On the main dev server this told Turbopack to crawl and file-watch the entire home directory, including the forge repo and all worktree copies of the app (13 at the time). The server sat at 300% CPU indexing and never became ready, so every request queued forever. A prior smoke test ("login: 200") false-passed because it was actually served by the old orphaned pre-merge server in its final seconds before dying.

Why: worktree slots run with --webpack (not Turbopack), so the root-widening workaround wasn't even needed there, and it's actively dangerous on the main server since Turbopack will index anything under the configured root.

How to apply: never set turbopack.root to a directory broader than the app's own worktree. If a worktree symlink issue resurfaces, look for a narrower fix. A warning comment was left in next.config.ts to prevent this from being reintroduced; check there first if dev server CPU pegs at high % with requests never completing.

[auto-memory session 69928070-35c5-4f35-a5cd-09393fe53e64, confidence 0.75, mode staged]