Reconsider exporting format_cropr() and dectect_mixture()

[sbuis]

Description

The functions format_cropr() and dectect_mixture() are currently exported in CroPlotR, making them part of the public API.

However, their intended scope and level of stability seem closer to internal utilities rather than user-facing functions. They are primarily used as intermediate processing steps and are not clearly documented as standalone features for end users.

This raises the question of whether they should remain exported.

Proposed change

• Move format_cropr() and dectect_mixture() to internal scope (remove @export and document them with @keywords internal if needed).
• Alternatively, if they are meant to be part of the public API:
  • Clarify their role in the documentation.
  • Strengthen argument validation.
  • Add explicit examples and tests covering user-facing usage.

Additional note

If backward compatibility is a concern, a deprecation cycle could be considered before fully unexporting these functions.