feat(issue#7): mp4 file input field

# Pull Request - Add MP4 File Input Functionality

## Description
This pull request introduces functionality allowing users to provide an **MP4 file** either by specifying its file path or uploading it directly within the application interface.

## Type of change
Please delete options that are not relevant.
- [ ] Bug fix (non-breaking change which fixes an issue)
- [x] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
- [ ] This change requires a documentation update

## How Has This Been Tested?
The following tests were conducted to verify functionality:
- **Unit Test for Input Field** – Ensured the input field accepts and validates MP4 file paths.
- **File Upload Test** – Verified file selection and upload feature allows users to provide MP4 files.
- **Integration Test** – Confirmed successful interaction between the input feature and downstream processing.
- **UI Verification** – Ensured proper rendering of the new interface options.

## Checklist
- [x] I have commented hard-to-understand areas of my code.
- [x] I have added docstrings to all public functions/methods.
- [x] I have used descriptive variable names to make my code easier to understand.
- [x] I have added tests that prove my fix is effective or that my feature works.
- [x] New unit tests pass locally with my changes.

## Unit test run by following commands
- python manage.py test home.tests
- python manage.py test videoapi.tests

## Related Issue(s)
Closes [#7](https://github.com/NM-TAFE/adv-ui-ocrroo-2025-AITMAR-TAFE/issues/7)