chore(deps): bump @babel/helpers and @babel/runtime 7→8 in /js

[gcko]

Type

• chore (dependency update)

Description

Consolidates the two Dependabot major babel bumps into a single PR so they land together — splitting them would leave a mixed babel 7/8 runtime in the lockfile, which is unsupported. Both are direct dependencies in js/package.json.

Package	From	To
@babel/helpers	7.29.7	8.0.0
@babel/runtime	7.29.7	8.0.0

Node floor decision

@babel/helpers@8.0.0 declares engines.node: "^22.18.0 || >=24.11.0". The repo previously pinned engines.node: ">=24", which would falsely permit node 24.0–24.10 — versions that do not satisfy helpers@8. To keep the declared floor honest, this PR raises:

"engines": { "node": ">=24.11" }

This is safe and changes nothing about what actually runs:

• CI uses actions/setup-node@v4 with node-version: 24 across all workflows (tests-js, tests-python, nightly, release, release-ui, address-dependabot), which resolves to the latest 24.x (currently ≥ 24.13) — already above the floor.
• Local/dev node is 24.13.0; .nvmrc pins 24.
• No Dockerfile in this repo pins a sub-24.11 node.
• The floor stays node-24-only (matching the prior >=24 intent) rather than re-opening node 22.

Note: @babel/runtime@8 removed its engines field entirely, so only @babel/helpers@8 drives the floor.

Incidental lockfile refresh

Regenerating the lockfile caught up 4 packages that were already within their existing caret ranges in package.json on main (the lockfile was stale — no package.json range changed): happy-dom 20.10.5→20.10.6, import-in-the-middle 3.0.2→3.1.0, posthog-js 1.387.0→1.390.2, baseline-browser-mapping 2.10.37→2.10.38.

Verification (from js/)

Gate	Result
pnpm install	✓ babel 8.0.0 resolved
CI=true pnpm install --frozen-lockfile	✓ (CI parity, lockfile consistent)
pnpm type:check	✓ pass
pnpm lint (biome)	✓ 655 files, no errors
pnpm test (vitest)	✓ 4007 passed, 5 skipped (182 files)
pnpm run build (next)	✓ compiled + static pages generated

No code changes were required for the major bump — babel 8 was a drop-in here.

PR Checklist

• Tests pass (pnpm test, type:check, lint, build all green)
• DCO sign-off on commit

User-facing changes

None. Internal dependency / build-tooling update only.

Closes #1437
Closes #1438