chore: import upstream snapshot with attribution

.github/pull_request_template.md

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+# 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/devGuide/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/devGuide/HowToAddNewLanguage.md#add-new-translation-tags) (for new translation tags only)
+
+### Translations (if applicable)
+
+- [ ] I ran [`scripts/counter_translation.py`](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/docs/counter_translation.md)
+
+### 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 run `task check` to verify linters, typechecks, and tests pass
+- [ ] I have tested my changes locally. Refer to the [Testing Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/DeveloperGuide.md#7-testing) for more details.