chore(pre-commit): enable test source formatting and build validation on push to main (#4067)

# Description of Changes

This PR improves the pre-commit workflow and formatting configuration to
enforce consistency and catch issues earlier in CI:

- **Pre-commit workflow (`pre_commit.yml`)**:
- Trigger now runs on `push` to `main` (previously scheduled weekly
only).
- Adds a `gradlew clean build` step to ensure the codebase compiles as
part of the pre-commit validation.
- Configures Java 17 using the Temurin distribution via
`actions/setup-java`.

- **.pre-commit-config.yaml**:
  - Updated `ruff` to version `v0.12.7` (from `v0.12.0`).
  - Updated `gitleaks` to `v8.28.0` (from `v8.27.2`).

- **Spotless configuration**:
- Added formatting for `test` sources across all Gradle modules
(`common`, `core`, `proprietary`, `stirling-pdf`).
- Ensures that test code follows the same formatting rules as production
code.

These changes help improve early feedback in development and CI by
integrating linting, formatting, and build checks directly into the
workflow on code pushes.


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## 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.