Feat/event access gate 368

[dDevAhmed]

Summary

Implements EventAccessGate to control event content visibility by access level (public, registered, organizer), and integrates it into the event detail flow to protect review submission UI.

Closes #368

What Changed

• Added reusable EventAccessGate component with:
  • Access levels: public, registered, organizer
  • Multiple required access levels support (single or array)
  • Default unauthorized fallback UI
  • Custom fallback override support
  • Helper function for access evaluation
• Exported EventAccessGate from shared UI molecules index for reuse across the app.
• Integrated gate into event details page:
  • Review creation section now requires registered attendee or organizer access
  • Unauthorized users see fallback messaging
• Fixed unrelated frontend compile error found during build verification:
  • Repaired malformed category schema in CreateEventForm

Why

This introduces a reusable, explicit access-control wrapper for event-specific UI sections and ensures unauthorized users get clear fallback messaging without breaking page-level access for public content.

Acceptance Criteria Mapping

• Restricts sections of UI: Implemented on review submission section.
• Displays fallback UI when unauthorized: Implemented default fallback.
• Supports multiple access levels: Implemented via single/array required access API.
• Reusable wrapper: Implemented as shared reusable component and exported.

Validation

• Frontend production build executed successfully after changes.
• Branch pushed and ready for PR review.