legacy UI (#4612)

# Description of Changes

<!--
Please provide a summary of the changes, including:

- What was changed
- Why the change was made
- Any challenges encountered

Closes #(issue_number)
-->

---

## Checklist

### General

- [ ] I have read the [Contribution
Guidelines](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/CONTRIBUTING.md)
- [ ] I have read the [Stirling-PDF Developer
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/DeveloperGuide.md)
(if applicable)
- [ ] I have read the [How to add new languages to
Stirling-PDF](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md)
(if applicable)
- [ ] I have performed a self-review of my own code
- [ ] My changes generate no new warnings

### Documentation

- [ ] I have updated relevant docs on [Stirling-PDF's doc
repo](https://github.com/Stirling-Tools/Stirling-Tools.github.io/blob/main/docs/)
(if functionality has heavily changed)
- [ ] I have read the section [Add New Translation
Tags](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md#add-new-translation-tags)
(for new translation tags only)

### UI Changes (if applicable)

- [ ] Screenshots or videos demonstrating the UI changes are attached
(e.g., as comments or direct attachments in the PR)

### Testing (if applicable)

- [ ] I have tested my changes locally. Refer to the [Testing
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/DeveloperGuide.md#6-testing)
for more details.

---------

Co-authored-by: Claude <[email protected]>
Co-authored-by: EthanHealy01 <[email protected]>
Co-authored-by: EthanHealy01 <[email protected]>

frontend/public/locales/en-GB/translation.json

@@ -1,4 +1,21 @@
 {
+  "toolPanel": {
+    "modePrompt": {
+      "title": "Choose how you browse tools",
+      "description": "Preview both layouts and decide how you want to explore Stirling PDF tools.",
+      "sidebarTitle": "Sidebar mode",
+      "sidebarDescription": "Keep tools alongside your workspace for quick switching.",
+      "recommended": "Recommended",
+      "chooseSidebar": "Use sidebar mode",
+      "fullscreenTitle": "Fullscreen mode - (legacy)",
+      "fullscreenDescription": "Browse every tool in a catalogue that covers the workspace until you pick one.",
+      "chooseFullscreen": "Use fullscreen mode",
+      "dismiss": "Maybe later"
+    },
+    "fullscreen": {
+      "showDetails": "Show Details"
+    }
+  },
   "unsavedChanges": "You have unsaved changes to your PDF.",
   "areYouSure": "Are you sure you want to leave?",
   "unsavedChangesTitle": "Unsaved Changes",