Refactor codebase to replace explicit constructors with Lombok annotations and remove boilerplat (#3415)

# Description of Changes

- **What was changed:**  
- Removed explicit constructor definitions annotated with `@Autowired`
across services, controllers, filters, and schedulers.
- Added Lombok’s `@RequiredArgsConstructor` to automatically generate
required-args constructors and eliminate boilerplate.
- Introduced other Lombok annotations (`@Data`, `@Getter`, `@Setter`,
`@EqualsAndHashCode`, `@NoArgsConstructor`) on model and API classes to
replace manual getters/setters and constructors.
- Standardized string comparisons to use the constant-first form (e.g.,
`"value".equals(variable)`).
- Cleaned up unused imports and organized OpenAPI configuration by
extracting default title/description constants.

- **Why the change was made:**  
  - To reduce repetitive boilerplate code and improve maintainability.  
- To leverage Lombok for cleaner, more consistent dependency injection
and data modeling.
  - To ensure a uniform coding style across the entire codebase.

#3406

---

## Checklist

### General

- [x] 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/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  

### 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.

src/main/java/stirling/software/SPDF/controller/api/ToSinglePageController.java

@@ -10,7 +10,6 @@ import org.apache.pdfbox.pdmodel.PDPage;
 import org.apache.pdfbox.pdmodel.PDPageContentStream;
 import org.apache.pdfbox.pdmodel.common.PDRectangle;
 import org.apache.pdfbox.pdmodel.graphics.form.PDFormXObject;
-import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.http.ResponseEntity;
 import org.springframework.web.bind.annotation.ModelAttribute;
 import org.springframework.web.bind.annotation.PostMapping;
@@ -20,6 +19,8 @@ import org.springframework.web.bind.annotation.RestController;
 import io.swagger.v3.oas.annotations.Operation;
 import io.swagger.v3.oas.annotations.tags.Tag;
 
+import lombok.RequiredArgsConstructor;
+
 import stirling.software.SPDF.model.api.PDFFile;
 import stirling.software.SPDF.service.CustomPDFDocumentFactory;
 import stirling.software.SPDF.utils.WebResponseUtils;
@@ -27,15 +28,11 @@ import stirling.software.SPDF.utils.WebResponseUtils;
 @RestController
 @RequestMapping("/api/v1/general")
 @Tag(name = "General", description = "General APIs")
+@RequiredArgsConstructor
 public class ToSinglePageController {
 
     private final CustomPDFDocumentFactory pdfDocumentFactory;
 
-    @Autowired
-    public ToSinglePageController(CustomPDFDocumentFactory pdfDocumentFactory) {
-        this.pdfDocumentFactory = pdfDocumentFactory;
-    }
-
     @PostMapping(consumes = "multipart/form-data", value = "/pdf-to-single-page")
     @Operation(
             summary = "Convert a multi-page PDF into a single long page PDF",