feat(identity-verification): sonderformat input

[Aaron-Ritter]

This pull request improves the clarity and organization of identity verification documentation. Changes include splitting and renaming existing pre-verification documentation, adding a new tutorial for phone identity pre-verification, and introducing deprecation warnings for outdated features.

Changes Made

• Refactor identity-verification documentation:

  • Separated email pre-verification and phone pre-verification instructions into distinct sections.
  • Improved document titles for consistency and clarity.
  • Added a draft Troubleshooting section for common issues.

• New tutorial added:

  • Provided step-by-step guidance for setting up phone identity pre-verification, aligning it with email pre-verification content.

• Deprecation notice:

  • Added deprecation warning for the legacy registration verification feature.