Add 'break-change' label and update release categories (#4806)

# Description of Changes

This pull request introduces a new label for breaking API changes and
updates the release configuration to categorize such changes in the
changelog. These updates help make it clearer when a pull request
contains a breaking change and ensure that these changes are highlighted
in release notes.

Label management:

* Added a new label `break-change` with a red color and a description to
indicate pull requests that introduce breaking API changes in
`.github/labels.yml`.

Release process improvements:

* Updated `.github/release.yml` to include a "Breaking Changes" section
in the changelog that groups pull requests labeled with `break-change`.

---

## 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/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
- [ ] 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

@@ -184,3 +184,6 @@
 - name: "codex"
   color: "ededed"
   description: "chatgpt AI generated code"
+- name: "break-change"
+  color: "FF0000"
+  description: "This PR introduces a breaking API change."

.github/release.yml

@@ -1,5 +1,9 @@
 changelog:
   categories:
+    - title: Breaking Changes
+      labels:
+        - break-change
+
     - title: Bug Fixes
       labels:
         - Bug