Remove book (#3065)

# Description of Changes

Please provide a summary of the changes, including:

- What was changed
- Why the change was made
- Any challenges encountered

Closes #(issue_number)

---

## 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/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)
- [ ] 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/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.

src/main/resources/templates/home-legacy.html

@@ -163,9 +163,6 @@
               <div
                 th:replace="~{fragments/card :: card(id='markdown-to-pdf', cardTitle=#{home.MarkdownToPDF.title}, cardText=#{home.MarkdownToPDF.desc}, cardLink='markdown-to-pdf', toolIcon='markdown', tags=#{MarkdownToPDF.tags}, toolGroup='convert')}">
               </div>
-              <div
-                th:replace="~{fragments/card :: card(id='book-to-pdf', cardTitle=#{home.BookToPDF.title}, cardText=#{home.BookToPDF.desc}, cardLink='book-to-pdf', toolIcon='book', tags=#{BookToPDF.tags}, toolGroup='convert')}">
-              </div>
             </div>
           </div>
 
@@ -198,9 +195,6 @@
               <div
                 th:replace="~{fragments/card :: card(id='pdf-to-csv', cardTitle=#{home.tableExtraxt.title}, cardText=#{home.tableExtraxt.desc}, cardLink='pdf-to-csv', toolIcon='csv', tags=#{tableExtraxt.tags}, toolGroup='convert')}">
               </div>
-              <div
-                th:replace="~{fragments/card :: card(id='pdf-to-book', cardTitle=#{home.PDFToBook.title}, cardText=#{home.PDFToBook.desc}, cardLink='pdf-to-book', toolIcon='book', tags=#{PDFToBook.tags}, toolGroup='convert')}">
-              </div>
             </div>
           </div>