Test real Darks FIDO2 passkey ceremonies across Edge, Chrome, and Firefox

[darkbyte-JS]

Goal

Exercise the installed Darks FIDO2 provider through real browser navigator.credentials.create() and get() ceremonies.

Acceptance criteria

• Test on Windows 11 24H2 or 25H2 with the provider enabled.
• Record browser and Windows versions, create/get results, discoverable/autofill behavior, and sanitized errors.
• Use disposable accounts only; attach no credentials, vaults, or personal logs.
• Update docs/COMPATIBILITY.md with confirmed results.

The existing CI browser test uses Chromium's virtual authenticator and does not cover the packaged provider.