Refactor UserInput schema and internal definitions

Changes

• No functional API endpoint changes in this update.

Other Changes

• Updated internal schema references:
  • Changed reference from OnboardingUserInput to UserInput in /APIOnboarding/properties/user_input.
  • Removed OnboardingUserInput definition.
  • Added new UserInput definition with similar structure.

Note: These changes affect internal schema definitions and do not alter any public API endpoints.