Add linting to the CI pipelines

[diofeher]

There are multiple steps to this PR:

1 - Adding ESLint and Prettier checks to the frontend pipeline
2 - Trigger verify.yml only if backend files are changed.
3 - Trigger frontend.yml only if frontend files are changed.
4 - Add linted files on the frontend (changed with prettier --write)

For linting frontend locally, use npm run lint.

This PR is meant to close #93 .

Checklist

• I have read the contribution guide.
• I have not used an AI coding assistant to create this PR.
• My contribution is compatible with the MPL-2.0 license and I have provided a DCO sign-off on all my commits.
• I have written all code in this PR myself OR I have marked all code I have not written myself (including modified code, e.g. copied from other places and then modified) with a comment indicating where it came from.

[diofeher]

Example run: https://github.com/diofeher/registry-ui/actions/runs/12564835424/job/35028392647

[abstractionfactory]

Thank you @diofeher added a few comments.

[diofeher]

@abstractionfactory Do you prefer to have the fixes together with the linting on this PR or in a separate PR? I'm planning to open another PR after this one with the fixes, but asking first before doing any work.

[abstractionfactory]

@diofeher whichever is easier for you :)

[diofeher]

@abstractionfactory thanks again for the support and comments! I just cleaned up the PR, should be good to go

[abstractionfactory]

@diofeher thank you for your work. One question: did you verify that the changed markdown files render correctly?

[diofeher]

@abstractionfactory Yep, I didn't know _ and * were the same on markdown, so I went to check if the generated pdf was the same.

[abstractionfactory]

Thank you @diofeher !