Save signatures to server (#5080)

# Description of Changes

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## 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)
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Stirling-PDF](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md)
(if applicable)
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- [ ] My changes generate no new warnings

### Documentation

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Tags](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md#add-new-translation-tags)
(for new translation tags only)

### Translations (if applicable)

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[`scripts/counter_translation.py`](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/docs/counter_translation.md)

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---------

Co-authored-by: Anthony Stirling <[email protected]>

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

@@ -2267,8 +2267,16 @@ defaultCanvasLabel = "Drawing signature"
 defaultImageLabel = "Uploaded signature"
 defaultTextLabel = "Typed signature"
 saveButton = "Save signature"
+savePersonal = "Save Personal"
+saveShared = "Save Shared"
 saveUnavailable = "Create a signature first to save it."
 noChanges = "Current signature is already saved."
+tempStorageTitle = "Temporary browser storage"
+tempStorageDescription = "Signatures are stored in your browser only. They will be lost if you clear browser data or switch browsers."
+personalHeading = "Personal Signatures"
+sharedHeading = "Shared Signatures"
+personalDescription = "Only you can see these signatures."
+sharedDescription = "All users can see and use these signatures."
 
 [sign.saved.type]
 canvas = "Drawing"