🌐 Sync Translations + Update README Progress Table (#3080)

### Description of Changes

This Pull Request was automatically generated to synchronize updates to
translation files and documentation. Below are the details of the
changes made:

#### **1. Synchronization of Translation Files**
- Updated translation files (`messages_*.properties`) to reflect changes
in the reference file `messages_en_GB.properties`.
- Ensured consistency and synchronization across all supported language
files.
- Highlighted any missing or incomplete translations.

#### **2. Update README.md**
- Generated the translation progress table in `README.md`.
- Added a summary of the current translation status for all supported
languages.
- Included up-to-date statistics on translation coverage.

#### **Why these changes are necessary**
- Keeps translation files aligned with the latest reference updates.
- Ensures the documentation reflects the current translation progress.

---

Auto-generated by [create-pull-request][1].

[1]: https://github.com/peter-evans/create-pull-request

---------

Co-authored-by: stirlingbot[bot] <195170888+stirlingbot[bot]@users.noreply.github.com>

src/main/resources/messages_eu_ES.properties

@@ -516,14 +516,6 @@ home.AddStampRequest.desc=Add text or add image stamps at set locations
 AddStampRequest.tags=Stamp, Add image, center image, Watermark, PDF, Embed, Customize
 
 
-home.PDFToBook.title=PDF to Book
-home.PDFToBook.desc=Converts PDF to Book/Comic formats using calibre
-PDFToBook.tags=Book,Comic,Calibre,Convert,manga,amazon,kindle
-
-home.BookToPDF.title=Book to PDF
-home.BookToPDF.desc=Converts Books/Comics formats to PDF using calibre
-BookToPDF.tags=Book,Comic,Calibre,Convert,manga,amazon,kindle
-
 home.removeImagePdf.title=Remove image
 home.removeImagePdf.desc=Remove image from PDF to reduce file size
 removeImagePdf.tags=Remove Image,Page operations,Back end,server side
@@ -848,19 +840,6 @@ compare.complex.message=One or both of the provided documents are large files, a
 compare.large.file.message=One or Both of the provided documents are too large to process
 compare.no.text.message=One or both of the selected PDFs have no text content. Please choose PDFs with text for comparison.
 
-#BookToPDF
-BookToPDF.title=Books and Comics to PDF
-BookToPDF.header=Book to PDF
-BookToPDF.credit=Uses Calibre
-BookToPDF.submit=Convert
-
-#PDFToBook
-PDFToBook.title=PDF to Book
-PDFToBook.header=PDF to Book
-PDFToBook.selectText.1=Format
-PDFToBook.credit=Uses Calibre
-PDFToBook.submit=Convert
-
 #sign
 sign.title=Sinatu
 sign.header=Sinatu PDF fitxategiak