feat(gql): Migrate fxa-settings from GraphQL to direct auth-client calls

[vbudhram]

Because

• The GraphQL layer (fxa-graphql-api) adds unnecessary complexity and latency between fxa-settings and fxa-auth-server

This pull request

• Adds account-storage.ts for unified localStorage-based account state management
• Adds useAccountData hook replacing GraphQL queries with direct auth-client calls
• Adds AccountStateContext for React state management with localStorage sync
• Adds POST /account/email_bounce_status endpoint to auth-server for email bounce detection
• Updates content-server account model to handle new localStorage structure
• Removes GraphQL dependencies from all signin, signup, and settings flows
• Removes PageMfaGuardWithGqlTest component (no longer needed)

Issue

Closes: TBD

Checklist

• My commit is GPG signed
• Tests pass locally (if applicable)
• Documentation updated (if applicable)
• RTL rendering verified (if UI changed)

Other Information

How to test:

1. yarn start and navigate to localhost:3030, create account and login
2. Verify account data loads (avatar, emails, 2FA status)
3. Open multiple tabs and verify session sync works