Add Phone Number Verification

[Mephistic]

Problem

In advance of what we expect to be a flood of new users submitting testimonies, we want to ensure that we can identify real people (as a first-layer attempt to filter out bots/spam). To that end, we should add phone number verification to MAPLE - allowing users to associate their account with a phone number via an SMS verification code, and filtering out testimony by unverified users by default. A phone number is imperfect, but a better indicator of "realness" than an email/Gmail account. We should take care to consider users using VOIP.

Success Criteria

• SMS Verification flow for user accounts
  • Open question: Where should this flow live? Account signup? Edit Profile page?
• Add Filter to Testimonies collection so we can filter out testimonies from unverfied users by default
  • Add "isVerifiedUser" field to Testimony in Typesense collection

Additional Links

• Figma: TBD

[Mephistic]

The UX designs are still TBD, so I think this issue will represent the work to get the backend portion working to sync an account with a phone number via Firebase Auth (likely linkWithPhoneNumber)

It may be helpful to also implement a bare-bones UI that calls the function for testing purposes