Move Babel packages from dependencies to devDependencies

[h-takeyeah]

Move Babel packages listed below from dependencies to devDependencies.

Description

The babel packages are build/transpile tools that consumers of @bbc/tv-lrud-spatial don't need at runtime.
Moving them from dependencies to devDependencies reduces disk usage of the consumers and might mitigate potential build tool's version conflict issues.

Motivation and Context

fix #59

How Has This Been Tested?

1. created a tarball file by using npm pack on the forked repo.
2. created empty npm project(example-lrud-app) and add @bbc/tv-lrud-spatial from a file.
3. check if no other packages is added to example-lrud-app.

summary:

youtaku@HP-ProDesk:/tmp/example-lrud-app$ npm install ~/work/lrud-spatial-fork/bbc-tv-lrud-spatial-0.0.16.tgz 

added 1 package, and audited 2 packages in 631ms

found 0 vulnerabilities
[snip]
youtaku@HP-ProDesk:/tmp/example-lrud-app$ npm why @babel/cli
npm error No dependencies found matching @babel/cli
npm error A complete log of this run can be found in: /home/youtaku/.npm/_logs/2026-06-26T06_41_15_039Z-debug-0.log

full result: babel-will-not-installed.txt

npm test failed

npm test against the commit was failed on my machine.

● LRUD spatial › Page with 3 candidates with equal distances to matching corners › should focus on candidate 1 when down, right, up is pressed

Test was executed on my machine: Ubuntu 26.04 LTS / Wayland / Chrome linux-144.0.7559.96 / puppeteer@24.36.1

full log: npm-test-against-b07b553fec0564a9e3336767397bc83ef9f3e8e5.txt

At least the current master branch code(13ff5d9) passes CI, and since this PR doesn't touch that code, I think the issue should be fine 👍 and Firefox does not reproduce the issue 🫤. I confirmed that by launching debug server with npm run server and visiting the page (http://localhost:3005/test/layouts/0c-3f-distance.html).

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[h-takeyeah]

BTW, I used Node.js v18.20.8 based on repository's .node-version. However, repository's workflow uses v24. Which one should I use?