style: improve formatting and import order consistency across codebase (#3761)

# Description of Changes

This pull request applies consistent formatting and import ordering
across the codebase. Specifically:

- Reordered imports according to the configured Spotless `importOrder()`
directive.
- Enabled formatting flags such as `trimTrailingWhitespace`,
`leadingTabsToSpaces`, and `endWithNewline`.
- Resolved inconsistencies in blank lines and spacing between imports
and annotations.
- Applied consistent formatting to annotations and method declarations.
- Removed unused or redundant import statements.

This change improves code readability, enforces a consistent style, and
prepares the codebase for future automated formatting checks.

---

## 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/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/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/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/DeveloperGuide.md#6-testing)
for more details.

build.gradle

@@ -170,16 +170,16 @@ subprojects {
     test {
         useJUnitPlatform()
     }
-    
+
     // Ensure all packaging tasks depend on writeVersion from root project
     tasks.withType(org.springframework.boot.gradle.tasks.bundling.BootJar) {
         dependsOn(rootProject.tasks.writeVersion)
     }
-    
+
     tasks.withType(Jar) {
         dependsOn(rootProject.tasks.writeVersion)
     }
-    
+
     tasks.withType(org.gradle.api.tasks.bundling.Zip) {
         dependsOn(rootProject.tasks.writeVersion)
     }