Hosted test vector corpus for CI?

[baylesj]

Background
Currently, Symphonia relies heavily on developers bringing their own private media collections and testing them locally using symphonia-check. While this is an excellent approach for broad coverage, it presents a few challenges as the project matures:

1. Regressions: Edge cases (like the CRC-protected Xing/Info tags in mp3: Xing/Info tag rejected on CRC-protected frames, VBR duration estimate ends up way off #516) are hard to test end-to-end in CI. While unit tests with mocked byte arrays work, they don't provide the confidence of parsing a real file.
2. Barrier to Entry: New contributors may not have a diverse corpus of files containing obscure codec features, making it hard for them to confidently verify their changes.

Proposal: A FATE-style Test Vector Corpus
To ensure long-term stability and make regression testing robust, I propose establishing a hosted test vector corpus, similar to FFmpeg's FATE suite or libvpx's test vectors.

The architecture could look like this:

1. Storage: A curated set of minimal, targeted test vectors (typically only a few seconds long to save space) hosted externally (e.g., GitHub Releases, an S3 bucket, or a separate Git LFS repo).
2. Integration: A script (e.g., a cargo xtask or a simple python script similar to benchtest.py) that downloads the corpus into the git-ignored testvec/ directory and verifies SHA-256 checksums.
3. CI Pipeline: The GitHub Actions workflow is updated to optionally fetch this minimal corpus and run integration tests (perhaps a headless version of symphonia-check) over the files.

Starting Point
We already have the infrastructure for downloading files in benchtest.py (which fetches from archive.org). We could start small. For example, I have a 3-second repro.mp3 file generated specifically to test the CRC-protection edge case from #516 that I would be happy to contribute as the first official regression test vector.

I've placed it in a public repository located here:

https://github.com/baylesj/symphonia-test-vectors

Would the maintainers (@pdeljanov , any other interested parties) be interested to moving towards a reproducible, CI-integrated test corpus? I'd be happy to help draft the fetch scripts or CI changes if there's interest in a specific hosting approach.