Fix Tibetan locale code to bo_CN and update translation ignore configurations (#3614)

# Description of Changes

## This PR also serves as a test for PR #3615.

### PR #3615 must first be merged to complete the test.

---

- **What was changed**  
- Replaced Tibetan locale code in README (`README.md`) from `zh_BO` to
`bo_CN`.
- Renamed resource file `messages_zh_BO.properties` to
`messages_bo_CN.properties` and updated its internal keys/translations.
- Updated the HTML fragment (`templates/fragments/languages.html`) to
reference `bo_CN` instead of `zh_BO`.
- Added a `[bo_CN]` section in `scripts/ignore_translation.toml` and
expanded ignore rules across multiple language sections to cover
additional codes.
- Enhanced `counter_translation.py` error handling: now catches
`ValueError` as `e` and logs file path and line number for easier
debugging.

- **Why the change was made**  
- The proper locale identifier for Tibetan is `bo_CN`, aligning with
[Localizely’s standard](https://localizely.com/locale-code/bo-CN/).
- Ensures consistency across code, resources, and templates so the
Tibetan translation loads correctly.
- Expanded ignore lists prevent false positives in translation coverage
checks, and improved error logging aids maintenance of the translation
scripts.

---

## 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.

README.md

@@ -151,7 +151,7 @@ Stirling-PDF currently supports 40 languages!
 | Spanish (Español) (es_ES)                    | ![89%](https://geps.dev/progress/89)   |
 | Swedish (Svenska) (sv_SE)                    | ![78%](https://geps.dev/progress/78)   |
 | Thai (ไทย) (th_TH)                           | ![71%](https://geps.dev/progress/71)   |
-| Tibetan (བོད་ཡིག་) (zh_BO)                     | ![79%](https://geps.dev/progress/79) |
+| Tibetan (བོད་ཡིག་) (bo_CN)                     | ![79%](https://geps.dev/progress/79) |
 | Traditional Chinese (繁體中文) (zh_TW)        | ![89%](https://geps.dev/progress/89)   |
 | Turkish (Türkçe) (tr_TR)                     | ![87%](https://geps.dev/progress/87)   |
 | Ukrainian (Українська) (uk_UA)               | ![89%](https://geps.dev/progress/89)   |