Replace reader role with viewer

[junminahn]

Description
Currently, the terms reader and viewer are used interchangeably for system roles. To standardize terminology, replace reader with viewer, as viewer is more commonly paired with editor. This ticket will update the system to reflect this change.

Technical Details

• Identify any hardcoded reader role Enums in the system.
• Check the database for any stored reader Enums.
  • If found, have a data migration plan to update these values.
• Review Keycloak roles generated by Terraform to identify any instances of reader.
  • If found, have a migration plan for Keycloak role updates.

Definition of Done (DOD)

• All instances of the reader role are updated to viewer, ensuring consistent terminology throughout the system.