Pin diva.js dependency to avoid fresh build failures

While trying to run Neon locally from a fresh setup, I encountered a build failure related to the `diva.js` dependency.

`package.json` currently specifies:
`"diva.js": "github:DDMAL/diva.js#master"` (https://github.com/DDMAL/Neon/blob/develop/package.json#L57C1-L58C1)

However, the `master` branch of `DDMAL/diva.js` no longer exists (the repository's default branch is `develop`). This causes yarn install to fail on a fresh setup:

`error An unexpected error occurred: ...Could not resolve ref: master`

Existing installs are unaffected because `yarn.lock` has the resolved commit cached. However, fresh installs or regenerated lock files will fail.

A temporary workaround is to pin diva.js to the last known working commit:
`"diva.js": "github:DDMAL/diva.js#5f530483f653db68af1cbb92bc8cc967b51763c3"`

Suggested fix: pin Neon to a stable diva.js v6 commit/tag, or update Neon to support diva.js v7.