Add ImageAssets for download

[NickHerrig]

Description

This PR is related to Issue #926.

The idea is to add ImageAssets for download along side the already great VideoAssets.

Type of change

This change is a non-breaking change.

• New feature (non-breaking change which adds functionality)
• This change requires a documentation update

How has this change been tested, please provide a testcase or example of how you tested the change?

To test the change you can install the assets submodule by running

pip install -e ".[assets]"

From there, test the new functionality with

from supervision.assets import download_assets, VideoAssets, ImageAssets

# Old method of downloading video assets still relevant.
download_assets(VideoAssets.VEHICLES)
"vehicles.mp4"

# New method of downloading image assts.
download_assets(ImageAssets.PEOPLE_WALKING)
"people-walking.jpg"

Any specific deployment considerations

I did my best to change the documentation, but please call out anything I missed and I will update.

To simplify the code, I also included a "Assets" class, and each enum has a 'filename' and a 'hash' tied to it reduce verbosity of building out the "VIDEO_ASSETS" dictionary. Let me know if this isn't a good direction, and I can refactor. The customer facing behavior is still the same.

Docs

• Docs updated? What were the changes:

Changes to the the docs/assets and changes to docstrings in the function were changed.

[NickHerrig]

@onuralpszr and @SkalskiP I changed the assets data structures a little bit, so let me know if you're not a fan of this direction.

Also this is still a draft as the photo placeholder included a single image for testing from inference
BASE_IMAGE_URL = "https://media.roboflow.com/inference/

I believe there should be a similar directory created how the video assets are under
https://media.roboflow.com/supervision/video-examples/ for image assets called https://media.roboflow.com/supervision/image-examples/

[Borda]

@copilot review this PR using the full structured format defined in .github/copilot-instructions.md

[Copilot]

Pull request overview

This PR adds first-class support for downloading image assets (via a new ImageAssets enum) alongside the existing video assets download workflow in supervision.assets.

Changes:

• Introduces ImageAssets and a BASE_IMAGE_URL, and consolidates image/video metadata into MEDIA_ASSETS.
• Updates download_assets() to accept ImageAssets in addition to VideoAssets and raw filename strings.
• Updates tests and docs to cover and document the new image assets functionality.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
src/supervision/assets/list.py	Adds ImageAssets, introduces shared Assets base, and builds unified MEDIA_ASSETS mapping.
src/supervision/assets/downloader.py	Extends downloader to accept image assets and use unified asset registry.
src/supervision/assets/__init__.py	Exposes ImageAssets from the package surface.
docs/assets.md	Documents image assets alongside video assets.
tests/assets/test_list.py	Updates asset list/value tests for new enums and unified mapping.
tests/assets/test_downloader.py	Adds downloader test coverage for downloading via ImageAssets.