Add error handling for optional field when left empty

[robinske]

Description

Deploying from the CodeExchange leaves an "empty string" without stripping the quotes. This change handles that edge case.

Checklist

• I ran npm test passkeys-backend locally and it passed without errors.
• I acknowledge that all my contributions will be made under the project's license.

Related issues

[Copilot]

Pull Request Overview

This PR introduces error handling for the optional ANDROID_APP_KEYS field when it is left as an empty string. Key changes include:

• Adding a test case for handling an empty string for ANDROID_APP_KEYS.
• Introducing the androidOrigins helper function to parse and sanitize the keys.
• Updating the request body to use the parsed origins in the API call.

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
passkeys-backend/tests/registration-start.test.js	Added test to ensure empty ANDROID_APP_KEYS is handled
passkeys-backend/functions/registration/start.js	Added androidOrigins to parse ANDROID_APP_KEYS and updated request body

Comments suppressed due to low confidence (1)

passkeys-backend/functions/registration/start.js:25

• [nitpick] Consider renaming 'androidOrigins' to 'parseAndroidOrigins' to more clearly express that this function parses the keys.

const androidOrigins = (keys) => {