Add B.Choppr by sjaehn

[kmturley]

Summary

• Adds B.Choppr, an LV2 plugin that cuts an audio stream into up to 16 repeated chops, each independently gated and panned.
• GPL-3.0. Used release 1.12.6 rather than the latest 1.12.8 — the latest release only ships a source tarball (no prebuilt binaries), while 1.12.6 has real Linux x64 builds. Dropped a redundant .zip duplicate of the .tar.gz (verified identical content via file count).

Test plan

• npx tsx src/validate.ts src/plugins/sjaehn/bchoppr/1.12.6/index.yaml passes

[github-actions]

VirusTotal Report:

• test/downloads/sjaehn/bchoppr/1.12.6/0-BChoppr-1.12.6-linux-amd64.tar.gz

[github-actions]

Destination urls:
Registry: https://open-audio-stack.github.io/open-audio-stack-registry/plugins/sjaehn/bchoppr
Site: https://studiorack.github.io/studiorack-site/plugins/sjaehn/bchoppr

[github-actions]

Plugin author notification:

@sjaehn — your plugin has been submitted to the Open Audio Stack registry. Please review this PR and let us know if the metadata (name, description, tags, files) is correct. To see a full list of all currently added plugins, click here.