Video source upload video cleanup

[jpggvilaca]

Summary

Follow up from #6981

• Deleting a video source should get delete uploaded video
• Replacing a video should delete the previous one

Final part of #6931

How to test

Checklist

• The PR title and description are clear and descriptive
• I have manually tested the changes
• All changes are covered by automated tests
• All related issues are linked to this PR (if applicable)
• Documentation has been updated (if applicable)

[github-actions]

⏱️ Backend import time — app.main

Accelerator	Cumulative (s)	Self (s)
cpu	4.868	0.004
xpu	4.844	0.004
cuda	5.331	0.004

[Copilot]

Pull request overview

This PR adds backend-side cleanup of uploaded “video_file” source media so that removing a video source (or replacing its uploaded video) also removes the previously uploaded file/directory from disk.

Changes:

• Add SourceMediaService.delete_video() and call it (best-effort) when deleting a video_file source.
• On video_file source updates, delete the old uploaded video when video_path changes.
• Wire SourceMediaService into the SourceUpdateService dependency and add unit/integration coverage for the cleanup behavior.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
application/backend/app/services/source_media_service.py	Adds delete_video() helper to remove uploaded video directories.
application/backend/app/services/source_service.py	Integrates best-effort media deletion into source delete/update flows.
application/backend/app/api/dependencies.py	Injects SourceMediaService into SourceUpdateService.
application/backend/tests/unit/services/test_source_media_service.py	Adds unit tests for delete behavior and safety boundaries.
application/backend/tests/integration/services/test_source_service.py	Verifies old-video cleanup is triggered on update/delete via mocked media service.

[github-actions]

🐳 Docker image sizes

Device	Size
cpu	4002.9 MB (3.91 GB)
xpu	10791.5 MB (10.54 GB)
cuda	10198.1 MB (9.96 GB)

[github-actions]

📊 Test coverage report

Metric	Coverage
Lines	60.0%
Functions	56.7%
Branches	51.5%
Statements	59.6%