refactor(common): remove unused temp directory & HTML unzip helpers, prune imports (#4857)

# Description of Changes

This pull request primarily removes several unused or redundant utility
methods related to temporary directory and file management across the
codebase. The changes help simplify the code and reduce maintenance
overhead by eliminating code that is no longer needed.

**Cleanup of temporary file and directory utilities:**

* Removed the `createTempDirectory` method from
`CustomPDFDocumentFactory`, which created uniquely named temporary
directories.
* Removed the `getTempDirectory` method from `GeneralUtils`, which
handled custom and default temporary directory configuration.

**Codebase simplification in file utilities:**

* Deleted the `deleteDirectory` and `unzipAndGetMainHtml` methods from
`FileToPdf`, which were used for recursively deleting directories and
extracting the main HTML file from a ZIP archive, respectively.
* Cleaned up unused imports in `FileToPdf` that were only needed for the
removed methods.

---

## 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)

- [ ] 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.

app/common/src/main/java/stirling/software/common/service/CustomPDFDocumentFactory.java

@@ -478,11 +478,6 @@ public class CustomPDFDocumentFactory {
         return file;
     }
 
-    /** Create a uniquely named temporary directory */
-    private Path createTempDirectory(String prefix) throws IOException {
-        return Files.createTempDirectory(prefix + tempCounter.incrementAndGet() + "-");
-    }
-
     /** Create new document bytes based on an existing document */
     public byte[] createNewBytesBasedOnOldDocument(byte[] oldDocument) throws IOException {
         try (PDDocument document = load(oldDocument)) {

app/common/src/main/java/stirling/software/common/util/FileToPdf.java

@@ -5,11 +5,8 @@ import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.UncheckedIOException;
 import java.nio.charset.StandardCharsets;
-import java.nio.file.FileVisitResult;
 import java.nio.file.Files;
 import java.nio.file.Path;
-import java.nio.file.SimpleFileVisitor;
-import java.nio.file.attribute.BasicFileAttributes;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Locale;
@@ -148,64 +145,6 @@ public class FileToPdf {
         }
     }
 
-    private static void deleteDirectory(Path dir) throws IOException {
-        Files.walkFileTree(
-                dir,
-                new SimpleFileVisitor<Path>() {
-                    @Override
-                    public FileVisitResult visitFile(Path file, BasicFileAttributes attrs)
-                            throws IOException {
-                        Files.delete(file);
-                        return FileVisitResult.CONTINUE;
-                    }
-
-                    @Override
-                    public FileVisitResult postVisitDirectory(Path dir, IOException exc)
-                            throws IOException {
-                        Files.delete(dir);
-                        return FileVisitResult.CONTINUE;
-                    }
-                });
-    }
-
-    private static Path unzipAndGetMainHtml(byte[] fileBytes) throws IOException {
-        Path tempDirectory = Files.createTempDirectory("unzipped_");
-        try (ZipInputStream zipIn =
-                ZipSecurity.createHardenedInputStream(new ByteArrayInputStream(fileBytes))) {
-            ZipEntry entry = zipIn.getNextEntry();
-            while (entry != null) {
-                Path filePath = tempDirectory.resolve(sanitizeZipFilename(entry.getName()));
-                if (entry.isDirectory()) {
-                    Files.createDirectories(filePath); // Explicitly create the directory structure
-                } else {
-                    Files.createDirectories(
-                            filePath.getParent()); // Create parent directories if they don't exist
-                    Files.copy(zipIn, filePath);
-                }
-                zipIn.closeEntry();
-                entry = zipIn.getNextEntry();
-            }
-        }
-
-        // Search for the main HTML file.
-        try (Stream<Path> walk = Files.walk(tempDirectory)) {
-            List<Path> htmlFiles = walk.filter(file -> file.toString().endsWith(".html")).toList();
-
-            if (htmlFiles.isEmpty()) {
-                throw new IOException("No HTML files found in the unzipped directory.");
-            }
-
-            // Prioritize 'index.html' if it exists, otherwise use the first .html file
-            for (Path htmlFile : htmlFiles) {
-                if ("index.html".equals(htmlFile.getFileName().toString())) {
-                    return htmlFile;
-                }
-            }
-
-            return htmlFiles.get(0);
-        }
-    }
-
     static String sanitizeZipFilename(String entryName) {
         if (entryName == null || entryName.trim().isEmpty()) {
             return "";

app/common/src/main/java/stirling/software/common/util/GeneralUtils.java

@@ -94,32 +94,6 @@ public class GeneralUtils {
         return tempFile;
     }
 
-    /*
-     * Gets the configured temporary directory, creating it if necessary.
-     *
-     * @return Path to the temporary directory
-     * @throws IOException if directory creation fails
-     */
-    private Path getTempDirectory() throws IOException {
-        String customTempDir = System.getenv("STIRLING_TEMPFILES_DIRECTORY");
-        if (customTempDir == null || customTempDir.isEmpty()) {
-            customTempDir = System.getProperty("stirling.tempfiles.directory");
-        }
-
-        Path tempDir;
-        if (customTempDir != null && !customTempDir.isEmpty()) {
-            tempDir = Path.of(customTempDir);
-        } else {
-            tempDir = Path.of(System.getProperty("java.io.tmpdir"), "stirling-pdf");
-        }
-
-        if (!Files.exists(tempDir)) {
-            Files.createDirectories(tempDir);
-        }
-
-        return tempDir;
-    }
-
     /*
      * Remove file extension
      *