[V2] feat(convert): add PDF/X export option (#5285)

# Description of Changes

This pull request adds support for converting PDF files to PDF/X format
in the frontend, alongside the existing PDF/A conversion. The changes
include UI updates, translation strings, configuration, and processing
logic to enable PDF to PDF/X conversion using the same backend endpoint
as PDF/A, with appropriate user options and warnings.

**PDF/X Conversion Support:**

- Added a new `ConvertToPdfxSettings` component for configuring PDF/X
conversion options, including output format selection and digital
signature warnings.
(`frontend/src/core/components/tools/convert/ConvertToPdfxSettings.tsx`)
- Updated the conversion settings UI to display PDF/X options when
converting from PDF to PDF/X.
(`frontend/src/core/components/tools/convert/ConvertSettings.tsx`)

**Configuration and Processing Logic:**

- Extended conversion constants and parameters to recognize PDF/X as a
target format, map it to the PDF/A backend endpoint, and ensure correct
file naming and processing behavior.
(`frontend/src/core/constants/convertConstants.ts`,
`frontend/src/core/hooks/tools/convert/useConvertOperation.ts`,
`frontend/src/core/hooks/tools/convert/useConvertParameters.ts`)
- Ensured that PDF/X conversions are processed separately per file,
similar to PDF/A.
(`frontend/src/core/hooks/tools/convert/useConvertOperation.ts`)

**UI and Translation Updates:**

- Updated translation strings to include PDF/X options, descriptions,
and warnings. (`frontend/public/locales/en-GB/translation.toml`)

<img width="366" height="998" alt="image"
src="https://github.com/user-attachments/assets/b28fa095-9350-4db2-a0b5-bddcf003fa46"
/>


<!--
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)

### Translations (if applicable)

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

### 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.

---------

Signed-off-by: Balázs Szücs <[email protected]>
Co-authored-by: Anthony Stirling <[email protected]>

frontend/src/core/components/tools/convert/ConvertSettings.tsx

@@ -17,6 +17,7 @@ import ConvertFromEmailSettings from "@app/components/tools/convert/ConvertFromE
 import ConvertFromCbzSettings from "@app/components/tools/convert/ConvertFromCbzSettings";
 import ConvertToCbzSettings from "@app/components/tools/convert/ConvertToCbzSettings";
 import ConvertToPdfaSettings from "@app/components/tools/convert/ConvertToPdfaSettings";
+import ConvertToPdfxSettings from "@app/components/tools/convert/ConvertToPdfxSettings";
 import ConvertFromCbrSettings from "@app/components/tools/convert/ConvertFromCbrSettings";
 import ConvertToCbrSettings from "@app/components/tools/convert/ConvertToCbrSettings";
 import ConvertFromEbookSettings from "@app/components/tools/convert/ConvertFromEbookSettings";
@@ -147,6 +148,9 @@ const ConvertSettings = ({
     onParameterChange('pdfaOptions', {
       outputFormat: 'pdfa-1',
     });
+    onParameterChange('pdfxOptions', {
+      outputFormat: 'pdfx',
+    });
     onParameterChange('cbrOptions', {
       optimizeForEbook: false,
     });
@@ -232,6 +236,9 @@ const ConvertSettings = ({
     onParameterChange('pdfaOptions', {
       outputFormat: 'pdfa-1',
     });
+    onParameterChange('pdfxOptions', {
+      outputFormat: 'pdfx',
+    });
     onParameterChange('cbrOptions', {
       optimizeForEbook: false,
     });
@@ -406,6 +413,19 @@ const ConvertSettings = ({
         </>
       )}
 
+      {/* PDF to PDF/X options */}
+      {parameters.fromExtension === 'pdf' && parameters.toExtension === 'pdfx' && (
+        <>
+          <Divider />
+          <ConvertToPdfxSettings
+            parameters={parameters}
+            onParameterChange={onParameterChange}
+            selectedFiles={selectedFiles}
+            disabled={disabled}
+          />
+        </>
+      )}
+
       {/* eBook to PDF options */}
       {['epub', 'mobi', 'azw3', 'fb2'].includes(parameters.fromExtension) && parameters.toExtension === 'pdf' && (
         <>

frontend/src/core/components/tools/convert/ConvertToPdfxSettings.tsx

@@ -0,0 +1,31 @@
+import { useEffect } from 'react';
+import { ConvertParameters } from '@app/hooks/tools/convert/useConvertParameters';
+import { StirlingFile } from '@app/types/fileContext';
+
+interface ConvertToPdfxSettingsProps {
+  parameters: ConvertParameters;
+  onParameterChange: <K extends keyof ConvertParameters>(key: K, value: ConvertParameters[K]) => void;
+  selectedFiles: StirlingFile[];
+  disabled?: boolean;
+}
+
+const ConvertToPdfxSettings = ({
+  parameters,
+  onParameterChange,
+  selectedFiles: _selectedFiles,
+  disabled: _disabled = false
+}: ConvertToPdfxSettingsProps) => {
+  // Automatically set PDF/X-3 format when this component is rendered
+  useEffect(() => {
+    if (parameters.pdfxOptions.outputFormat !== 'pdfx-3') {
+      onParameterChange('pdfxOptions', {
+        ...parameters.pdfxOptions,
+        outputFormat: 'pdfx-3'
+      });
+    }
+  }, [parameters.pdfxOptions.outputFormat, onParameterChange]);
+
+  return null;
+};
+
+export default ConvertToPdfxSettings;