dynamic port for UI from 8080 up (8081 etc)

[Frooodle]

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)

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Checklist

General

• [ ] I have read the Contribution Guidelines
• [ ] I have read the Stirling-PDF Developer Guide (if applicable)
• [ ] I have read the How to add new languages to Stirling-PDF (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 (if functionality has heavily changed)
• [ ] I have read the section 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 for more details.