Decide future contract for legacy applicability matrix

During the #906 (closed) coverage-assumption review, B084 accepted the current helper-level behavior of util_app_con_contradictions_redcap(): it combines a fixed concept applicability with the supplied datatype applicability vector and returns the current applicability scores.

This is only a characterization of legacy behavior. The applicability matrix originates from the dataquieR 1 era and is only partly aligned with the current dq_report2()/pipeline applicability logic.

Existing historical issues such as #46 (closed), #79 (closed), #91 (closed), and #204 (closed) are closed or cover narrower historical defects. We should keep a current follow-up that explicitly decides what should happen with this legacy surface.

Questions to settle:

  • Is pro_applicability_matrix() still part of the supported user-facing API, or should it be deprecated/soft-deprecated?
  • If it remains supported, should its scoring be aligned with current indicator-level applicability and dq_report2() behavior?
  • Should helper functions such as util_app_con_contradictions_redcap() keep their current score semantics or be replaced by condition/applicability classes used elsewhere?
  • How should old applicability levels be documented when datatype applicability and concept applicability are mixed?

Acceptance checklist:

  • Decide supported/deprecated status of pro_applicability_matrix().
  • Document the intended relationship to dq_report2() applicability.
  • Decide whether helper-level scores such as "1"/"3" remain meaningful.
  • Update tests to distinguish legacy characterization from intended future contract.
  • Update website/developer documentation accordingly.
Edited by Stephan Struckmann