Rollback: Add toggle for diff display (closes #18518)

[AndyButland]

Description

#18518 reports a concern when there are large documents with deeply nested block structures, the diff display on the rollback is not only not useful, but also severely impacts performance such that the browser cannot render the view.

Given that, I considered it would be safer to introduce a toggle to select when you want to view the diffs, and they are only shown when you choose to do so.

That's what's added in this PR.

Note that I've updated the translation files are part of this - using AI of course. This was necessary given the existing text has now been split across two keys, so the updates should be applied to all translations to avoid them no longer making good sense with the updated UI.

Change Summary

• Adds a checkbox toggle to the rollback modal that controls whether diff computation and highlighting is shown
• Default is OFF to prevent performance issues with documents containing large nested JSON
• Only computes diffs when the user explicitly enables the toggle
• Adds showDiff localization key to all language files that have rollback translations

Testing

To test, open a document's rollback view and note that now the diff is not currently displayed unless you toggle it on. Then the diff will be displayed as you choose different versions until you toggle it off again.

[Copilot]

Pull request overview

This pull request adds a toggle checkbox to the rollback modal that controls whether diff computation and highlighting is displayed. The default state is OFF to prevent performance issues when comparing documents with large nested JSON content.

Changes:

• Added a _showDiff state property (default: false) and checkbox toggle to control diff display
• Modified diff computation to only run when the toggle is enabled
• Added a #getPlainValue() helper to display property values without diff highlighting
• Updated 25 language files with new showDiff translation key and simplified diffHelp text

Reviewed changes

Copilot reviewed 27 out of 27 changed files in this pull request and generated 1 comment.

File	Description
rollback-modal.element.ts	Adds toggle functionality to conditionally compute and display diffs, improving performance for large documents
en.ts, da.ts, de.ts, etc. (25 language files)	Adds showDiff translation key and simplifies diffHelp text across all supported languages

Comments suppressed due to low confidence (1)

src/Umbraco.Web.UI.Client/src/packages/documents/documents/rollback/modal/rollback-modal.element.ts:1

• When the toggle is turned OFF, the _diffs array is not cleared. This means the old diff data remains in memory even though it's not displayed. Consider adding else { this._diffs = []; } to explicitly clear the diffs when the toggle is disabled to free up memory, especially given this feature is meant to address performance issues with large content.

import { UMB_DOCUMENT_ENTITY_TYPE } from '../../constants.js';

[leekelleher]

Tested out, works as described. 🚀 It's a much nicer experience.

I made an adjustment, by changing the uui-checkbox to a uui-toggle, in terms of UI semantics, the checkbox implies selection and toggle implies activation.