Refactor WebAuthn public key algorithms

[aduth]

🛠 Summary of changes

Some small revisions and clean-up around WebAuthn supported algorithms.

Why?

• Reduce repeated code with pubKeyCredParams object structure
• Improve readability of possible and supported algorithms
• Add sources for referencing, to improve understanding and help ensure accuracy in the future
• Optimize output size by leveraging TypeScript const enum inlining (minified brotli size reduction of webauthn-setup.js by about 2%, from 1.17kb to 1.15kb)
  • As a follow-up task, we should consider porting most of our enum to const enum to take advantage of the same optimization
• Eliminate duplicate algorithm in server-side WebAuthn gem configuration (PS256 was previously both a default and concatenated)

📜 Testing Plan

Verify no regressions in setting up a WebAuthn authentication method.

Ensure server-side algorithm configuration includes only unique values (this would produce false on main):

echo "WebAuthn.configuration.algorithms.uniq == WebAuthn.configuration.algorithms" | rails c
# => true