Pass labels as props in RichEditor to make them translatable

[SarahW91]

Description

Problem: RichEditor hardcodes several user-facing strings ("Attach files", "Uploading file...", "Preview math equations", image alt text). Since this package has no translation workflow of its own, consuming packages cannot translate these strings, leading to non-translatable UI elements (e.g. the "Attach files" button in invenio-requests' comment editor).

This PR introduces an optional labels prop (object) with sensible English defaults, matching current behavior. Consuming packages can override any subset of labels with translated strings without needing to fork or patch the component. Fully backwards-compatible — no labels prop means unchanged behavior.

Disclaimer: I used Claude to help me with this PR since I'm not a React/JS specialist.

I tested this code locally and it works and allows to the mentioned labels to be translated, if props are passed by invenio-requests. I'll create a separate PR there for passing the translatable strings.

Checklist

Ticks in all boxes and 🟢 on all GitHub actions status checks are required to merge:

• I'm aware of the code of conduct.
• I've created logical separate commits and followed the commit message format.
• I've identified the copyright holder(s) and updated copyright headers for touched files (>15 lines contributions).
• I've NOT included third-party code (copy/pasted source code or new dependencies).
  • If you have added third-party code (copy/pasted or new dependencies), please reach out to an architect on Discord.

Reminder

By using GitHub, you have already agreed to the GitHub’s Terms of Service including that:

1. You license your contribution under the same terms as the current repository’s license.
2. You agree that you have the right to license your contribution under the current repository’s license.

[SarahW91]

PR in invenio-requests: inveniosoftware/invenio-requests#644

[mkloeppe]

This looks good. Default labels are used when no additional labels are provided through props.

[mkloeppe]

Suggested change

	return { ...defaultLabels, ...this.props.labels };
	const { labels } = this.props;
	return { ...defaultLabels, ...labels };

[mkloeppe]

Just to please the linter. Destructuring props before using them is the way.

[Samk13]

Thanks for this!
the labels are wired into the existing:
attachment button
upload message
preview tooltip/title
Should we also forward labels through RichInputField? It currently constructs RichEditor without passing that prop.

Have you tested changing languages after mounting is working? TinyMCE ignores initialization configuration changes after launch, and the toolbar labels are captured during setup.

Screenshots are always welcome showing the translated attachment button, upload message, and preview tooltip/dialog, plus an example confirming that omitted labels retain their English defaults. Thanks!

[SarahW91]

Good points, I'll adjust RichInputField as well!

As for the screenshots:

"Attach files" does get translated:

No translation for "preview math equations" was found, so the default is used:

Wasn't quick enough with a screenshot for the upload message ;) Couldn't find the image description message in the UI.

Switching back and forth between languages didn't seem to be a problem, neither for the button nor the toolbar labels.