fix(pipeline): Update isZip method to validate against filename extensions, and keep comic archives zipped (#4741)

# Description of Changes

This pull request updates the logic for detecting and handling zip files
in the `PipelineProcessor` to distinguish between standard zip files and
comic book archive formats (CBZ/CBR). The changes ensure that files with
`.cbz` extensions are not treated as zip files for unzipping purposes.

**Update to zip file detection and extraction:**

* Modified the `isZip` method to take an optional `filename` parameter
and treat files ending with `.cbz` or as non-zip, preventing them from
being unzipped automatically.
* Updated all usages of `isZip` to pass the filename where available,
ensuring the new logic is applied during output file processing and
nested unzipping.

Closes: #4740


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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)
- [ ] 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.

---------

Signed-off-by: Balázs Szücs <bszucs1209@gmail.com>

app/core/src/main/java/stirling/software/SPDF/controller/api/pipeline/PipelineProcessor.java

@@ -289,7 +289,7 @@ public class PipelineProcessor {
             newFilename = removeTrailingNaming(extractFilename(response));
         }
         // Check if the response body is a zip file
-        if (isZip(response.getBody())) {
+        if (isZip(response.getBody(), newFilename)) {
             // Unzip the file and add all the files to the new output files
             newOutputFiles.addAll(unzip(response.getBody()));
         } else {
@@ -379,14 +379,25 @@ public class PipelineProcessor {
         return outputFiles;
     }
 
-    private boolean isZip(byte[] data) {
+    private boolean isZip(byte[] data, String filename) {
         if (data == null || data.length < 4) {
             return false;
         }
+        if (filename != null) {
+            String lower = filename.toLowerCase();
+            if (lower.endsWith(".cbz")) {
+                // Treat CBZ as non-zip for our unzipping purposes
+                return false;
+            }
+        }
         // Check the first four bytes of the data against the standard zip magic number
         return data[0] == 0x50 && data[1] == 0x4B && data[2] == 0x03 && data[3] == 0x04;
     }
 
+    private boolean isZip(byte[] data) {
+        return isZip(data, null);
+    }
+
     private List<Resource> unzip(byte[] data) throws IOException {
         log.info("Unzipping data of length: {}", data.length);
         List<Resource> unzippedFiles = new ArrayList<>();
@@ -410,7 +421,7 @@ public class PipelineProcessor {
                             }
                         };
                 // If the unzipped file is a zip file, unzip it
-                if (isZip(baos.toByteArray())) {
+                if (isZip(baos.toByteArray(), filename)) {
                     log.info("File {} is a zip file. Unzipping...", filename);
                     unzippedFiles.addAll(unzip(baos.toByteArray()));
                 } else {