🌐 Sync Translations + Update README Progress Table (#2907)

### 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_ja_JP.properties

@@ -768,7 +768,6 @@ autoSplitPDF.selectText.3=スキャンしたPDFファイルをアップロード
 autoSplitPDF.selectText.4=仕切りページは自動的に検出、削除されるので、最終的な文書はきれいに仕上がります。
 autoSplitPDF.formPrompt=Stirling-PDF仕切り用紙を含むPDFを送信:
 autoSplitPDF.duplexMode=両面モード (表裏スキャン)
-autoSplitPDF.dividerDownload1=ダウンロード '自動仕切り用紙 (最小).pdf'
 autoSplitPDF.dividerDownload2=ダウンロード '自動仕切り用紙 (手順書付き).pdf'
 autoSplitPDF.submit=送信