chore(labeler): add new 'v2' label and expand matching rules (#4172)

# Description of Changes

- **Added** a new `v2` label with `base-branch` targeting `V2`
- **Extended** the 'UI' label matching to include `frontend/**` files
- **Extended** the 'Scripts' label matching to include `docker/**` files
- **Removed** duplicate `devTools/.*` entry from 'Devtools' label
configuration

---

## 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/devGuide/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
- [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/devGuide/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/devGuide/DeveloperGuide.md#6-testing)
for more details.

.github/labels.yml

@@ -83,6 +83,7 @@
   color: "DEDEDE"
 - name: "v2"
   color: "FFFF00"
+  description: "Issues or pull requests related to the v2 branch"
 - name: "wontfix"
   description: "This will not be worked on"
   color: "FFFFFF"