feat(ci): run frontend reproducibility in each PR

[AntonioVentilii]

Motivation

Given recent reproducibilities issues with bumping Tailwind v4 (see one of the fixes here), we include the CI that checks the frontend reproducibility in each PR, and on main.

Furthermore, once this PR is merged, we will add the check among the compulsory ones to be able to merge any PR.

[peterpeterparker]

I would run it on package-lock change.

[AntonioVentilii]

@peterpeterparker I changed the pull_request parameter to be only for that. But what do you think of having a permanent check on main? Too redundant?

[peterpeterparker]

Not sure it's redundant, just asking my self about workload. The script performs 10 npm ci && npm run build in a row.

[AntonioVentilii]

@peterpeterparker then I will remove the trigger by main for now (we didn't have it before anyway), and revisit in case there we find a case. So, just on pull_request on package-lock for now

[peterpeterparker]

LGTM, thx