chore: upgrade @babel/core to ^7.29.6 to address CVE-2026-49356

Refreshed the yarn.lock so all transitive @babel/core instances resolve to
7.29.7 (>= 7.29.6), fixing the arbitrary file read via sourceMappingURL comment.

Generated with [Linear](https://linear.app/sourcebot/issue/SOU-1357/sourcebot-devsourcebot-cve-2026-49356-babelcore-arbitrary-file-read#agent-session-c9dbdeec)

Co-authored-by: linear-code[bot] <222613912+linear-code[bot]@users.noreply.github.com>

Author: brendan-kellam