feat(compress): expose linearize PDF option on the UI (#4843)

# Description of Changes

TLDR:


- Added a new checkbox in the UI for linearizing PDFs
- Updated `CompressController` to support PDF linearization
- Added new localization key for linearize option in messages properties
file

<img width="604" height="858" alt="image"
src="https://github.com/user-attachments/assets/3e7fb3c1-247d-45b1-b00b-fd19a9888d28"
/>




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## Checklist

### General

- [X] I have read the [Contribution
Guidelines](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/CONTRIBUTING.md)
- [X] 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)
- [X] I have performed a self-review of my own code
- [X] 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)

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

### Testing (if applicable)

- [X] 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 <bszucs1209@gmail.com>

app/core/src/main/java/stirling/software/SPDF/controller/api/misc/CompressController.java

@@ -774,11 +774,11 @@ public class CompressController {
             this.streamLength = image.getCOSObject().getLength();
             this.imageType = getImageType(image);
             this.decodeParams = generateDecodeParamsHash(image);
-            this.metadataHash = this.generateMetadataHash(image);
+            this.metadataHash = ImageIdentity.generateMetadataHash(image);
         }
 
         // Generate hash of image metadata
-        private String generateMetadataHash(PDImageXObject image) {
+        private static String generateMetadataHash(PDImageXObject image) {
             try {
                 StringBuilder metadata = new StringBuilder();
 

app/core/src/main/resources/messages_en_GB.properties

@@ -1329,6 +1329,7 @@ compress.title=Compress
 compress.header=Compress PDF
 compress.credit=This service uses qpdf for PDF Compress/Optimisation.
 compress.grayscale.label=Apply Grayscale for Compression
+compress.linearize.label=Linearize PDF for faster web viewing
 compress.selectText.1=Compression Settings
 compress.selectText.1.1=1-3 PDF compression,</br> 4-6 lite image compression,</br> 7-9 intense image compression Will dramatically reduce image quality
 compress.selectText.2=Optimisation level:

app/core/src/main/resources/templates/misc/compress-pdf.html

@@ -45,6 +45,12 @@
                     <label for="grayscaleCheck" th:text="#{compress.grayscale.label}">
                         Convert images to grayscale for better compression
                     </label>
+                </div>
+                  <div class="form-check mt-3">
+                    <input id="linearizeCheck" name="linearize" type="checkbox" value="true">
+                    <label for="linearizeCheck" th:text="#{compress.linearize.label}">
+                        Linearize PDF for faster web viewing
+                    </label>
                 </div>
                 </div>
               </div>